Your comments as to what's below and/or new comments and questions can be forwarded to my e-mail address - saltcorner@cs.com. Take into consideration that I'm a 'Senior Citizen' and growing a little slower every day. Your e-mail may be one of twenty or more received daily, and between travel, both pleasure and business, answering may take a week or more.
Dear Bob:
I purchased and read your Sand Secrets books last night, however, my local aquarium expert suggests that live sand will dissolve over time? And as such, he claims he has added approximately 60 to 70 lbs. of sand to his Jaubert/NNR system over a period of 4 years. He also told me that if I put the screen between the anoxic sand layer and the upper sand layer that due to sand dissolving this screen will eventually work its way to the bottom, resting on the screen on the eggcrate and I will eventually have to redo this part? (he did not put the screen in at all, however, I do understand why it is needed though from your book). He also claimed that if the sand is not cleaned on a regular basis that it would release hydrogen sulfide and toxic gasses that killed the first two to three sets of fish he put in the tank! This cannot really be so from what I read in your book - can it? This does not sound right to me. I am doing a 90 gallon and am on my way to Lowes to purchase the eggcrate, etc., to get the plenum going.
I found your web-site (www.saltcorner.com) very informative and helpful.
Thanks,
Tom
Hi Tom,
Thanks for your letter and have often heard some of these statements. As for sand dissolving, it occurs in any type aquarium, especially if it's an aragonite material. That's why it was used in the first place! I've added new sand to all of my past plenum systems, and that of client tanks. And that usually happened about twice a year where some new sand was funneled through a length of PVC pipe to several areas and raked smooth with a long handled homemade acrylic rake.
As for the dividing screen getting close to the bottom grid, I guess you could say that sounds quite logical, however, I don't know of it happening, even in systems that are now eight years old. It seems like the majority of the sand dissolves in the upper layers. Yet, could be in thirty years the dividing screen might be much closer to the grid screen. But redoing the aquarium would not be needed because a couple of screen layers on top of the grid is not going to cause a situation where the aquarium would have to be torn down. That's alarmist thinking. And more and more people are leaving the dividing screen out unless they plan on putting many digging animals in the system.
The hydrogen sulfide thought is ridiculous! In fact, plenum systems have less than what other type beds have because of its greater oxygen content. What killed his fishes certainly was not hydrogen sulfide! However, as stated in my booklet, sand should be vacuumed monthly as it's just a part of good housekeeping. Would you never dust your home?
Glad you liked the website, as I have put much effort into it to help all hobbyists.
Hope this helps,
Bob
Dear Dr. Bob Goemans
After more than fifteen years of keeping discus, I have decided about one year ago, to try a reef tank. In the next six months I will move to a new house and intend to install my first reef aquarium. When I decided to become a reef keeper, I begun reviewing the magazines (FAMA and TFH) that I have subscribed to during the last five years. I ordered some books in order to prepare my entry in this new world. I have now in my computer a database of more than 250 different themes.
Among those articles and books I must say your lessons in Sand-Mail and Julian Sprung's Reef Notes, both in FAMA and your booklets "Live Sand Secrets" and "Marine Algae Control Secrets" and both volumes of "The Reef Aquarium" by Julian Sprung are excellent!
I feel in this moment I am "almost ready" but as you are in my opinion the greatest opinion leader in this hobby and some doubts still remain, I would like to ask for your help and comments on the set-up I plan to install:
Aquarium dimensions: 150cm L x 65cm W x 65cm H with overflow. I intend to install a plenum in a sump. The plenum will be built as follows: Eggcrate - 1" deep with two inches of sand, then the dividing screen, then two more inches of same type sand.
About the plenum I have my first questions:
1. In your booklet you mention that the "rule of thumb" for a plenum in a sump is that the sump have more or less two thirds of the surface of the main tank. Do you think I can handle this tank having a sump with 85 cm L x 45 cm W? My idea is using one of my old cabinets.
2. In the same booklet you refer to an aquarist having excellent results in nitrate reduction by using a water flow rate of 15 gallons per hour for a 30 gallon auxiliary tank. What is the pump ideal flow rate for my tank and what would be the maximum flow rate allowed?
I intend to install in my aquarium a calcium reactor and a protein skimmer and I have two more doubts:
1 - When replacing the evaporated water, shall I use RO/DI water only, or shall I correct it with any additives?
2 - The protein skimmers readily available in Portugal are: Turbo Berlin (Red Sea), Turbofloter 1000 (Aqua Medic), Automatic Skimmer 230/3 - (Tunze, and they claim to be "plankton safe." What would you choose?
In the show tank I intend to install a 1" deep sand bed, is that ok?
Going to illumination, I intend to install a device with two 250W, 10K German metal halide bulbs, and two 30W fluorescent actinic bulbs. Do you think this will be enough to keep soft and stony corals and other inverts? If available should I choose 20K metal halide bulbs?
Regarding the powerheads, how many, with what flow rate, and what would be the ideal position for them?
Is there any trademark plankton safe?
In Portugal I don't have the possibility of getting live sand, so I intend to order from USA, some of Marc Weiss products to help start my aquarium; what are the products that you would advise?
As you can see for a person "almost ready" I have a lot a doubts; I hope you will be patient enough to help me!
Thanks in advance for your help.
César Silvério
Portugal
Dear César,
Thank you for your kind remarks and let me note that I prefer to be addressed as 'Bob' not Dr. Goemans. My doctorate is not in the medical field, and feel that 'Dr.' should be more properly applied to those with a medical degree.
Let me address first your decision/question to place the plenum in an interconnected tank, i.e., auxiliary plenum system. This method has become widely accepted, as many aquarists simply do not like the look of a very deep bed in their main system. Not only has it resolved that issue, it is proving to be more easily maintained when not cluttered with live rock formations and various coral animals. My old 180 gallon solar powered reef aquarium had a 60 gallon plenum tank under the main tank. However, that main tank had 27 fishes and was fed as many as six times a day. I found that size interconnected plenum system not capable of keeping nitrates below 5 ppm, as originally desired. Its nitrate level stayed about 7 to 8 ppm. Therefore, it only seems reasonable to assume a slightly bigger plenum system or less feeding would have reached that goal. Because of this personal experience, I now think the interconnected plenum system not be any smaller than half the size of the main tank when it comes to surface area. And yours should do nicely! Of course many aquarists don't feed that often, but I couldn't pass up all my little friends every time I passed by without giving them a treat. Besides, I was using a new phosphate removing product from England called ROWAphos that is quite remarkable. I was also using the Merck Test Kit 1.14445.0001, which is without doubt extremely accurate. Keep phosphate below 0.015 ppm and you'll never be bothered with unwanted forms of algae! And this is the only somewhat reasonably priced kit that I know of that will accurately measure this extremely low level.
As for flow rate between the plenum tank and main system, feedback and personal experience show that something near half its volume per hour seems to work the best. If your auxiliary plenum tank is about 80 gallons, then forty gallons per hour should flow between them. Again, this seems to work the best for everyone that has tried it, yet flow could be somewhat more or less.
My preference for makeup water continues to be just plain RO/DI water, with no additives. I am not comfortable with the wide array of additives on the market. Not because they are of inferior quality, but because of improper use! Too many aquarists think a little more is better when it come to dosage rates. Not true, and confusion remains about their need. Often, there's duplication of various elements and compounds and that leads to precipitation of much of it. And, if there is a calcium reactor in use, much of what would be added to RO/DI water is duplicated in the reactor's effluent. Yet, in certain circumstances, these RO/DI additives do have a good value, however, each system should be evaluated as to their need.
When it comes to the three available skimmer brands, I or my clients have or are using all of them. They are all excellent products, however, you are right about the more plankton safe Tunze models. If that's a concern, the Tunze model would be an excellent choice.
When it comes to the depth of the sandbed in the show tank, I've done almost the same thing in my old 180 system. In some places it was about two inches deep and sand grain size was about 2 mm.
As for lighting, your six foot system will probably need three 250W 10K MH lamps and possibly two full length 50/50 type fluorescent lamps to adequately light the entire tank. However, for now, more light loving corals could be grouped near the two MH lamps and those animals not needing bright light placed in the lower light areas. It all depends upon your ability to pay the electric bill! And I've found the 20K lamps to make the environment look too blue. I prefer the 10K's. Of course either would suffice for the animals, but to the human eye, my preference is the 10K's.
When it comes to powerheads, I've grown to like the various models in the Tunze line. I've had great success with them, however, they are quite pricey when compared to other brands. As for placement, the rear corners are two of the best places with each facing forward and slightly to the center of the aquarium. Placing them on a wavemaker so as to alternate their flows is the best approach, and the Tunze units are built to handle the on/off routine without any heat buildup or additional wear. My reef system also used two Tunze Turbelle 3000/2 system pumps for consistent water movement in the aquarium. With each Tunze capable of delivering about 700+ gallons per hour, system surges could at times exceed 2000 gallons per hour. And that's not counting the flow from my interconnected plenum system. That entire system can be seen by visiting my new website at www.saltcorner.com and clicking on the Photo Gallery button (the lower right button). Which by the way could contain system photos of your system (or others) if they become available to me.
I should also note the flows that impact the animals must be related to what they would incur in the wild. That's not easy to judge, but commonsense should be used. System overall water movement is more of a general concept that helps with preventing dead spots and providing good gas exchange. It should never be confused with direct flow against or around an animal.
As for 'live' plankton foodstuffs, I'm not sure what's available in your area. Yet, caution must be used when using any live foodstuffs as unwanted organisms can easily be introduced. My preference is would products such as Julian Sprung's Marine Snow, Marc Wiess Combo-Vital and/or Kent Marines Chromaplex Phytoplankton/Phytoplex Phytoplankton. Also there is a new phytoplankton product called BioPlankton from Liquid Life USA. You can check it out by visiting my website and clicking on their banner on the advertisers page.
For starting the microbial processes, there are many excellent products. And if possible, an aquarium's sandbed should be microbially well established before adding too much live rock. Starting a system with more nutrients than what there is in the way of bacteria to use them simply does not make sense! Why give unwanted forms of algae an opportunity to gain a foothold. Get the nutrient 'users' established first, then introduce a supply of their needs. Patience pays off in the long-term! And, could be the sand your going to order is available 'live.' Some of these prepackaged brand sand grains are already coated with bacteria. Even though dormant, these bacteria will quickly awaken and begin colonizing the substrate. Check it out!
Hope this helps and keep me posted,
Bob
Bob,
I have been satisfied with Marine Technical Concepts (MTC) CalPro Calcium Reactor I had running for a number of years. However, it has finally "died" on me and I'm in the market now for a replacement. I believe I bought it based on your recommendations (I always consider your recommendations before making a major purchase of any marine reef-related item.) Quite frankly, a replacement MTC CalPro seems pricey. But I'm totally in the dark on what I should buy since I haven't paid attention to changes in calcium reactor technologies, since buying my original. Is it possible that given the current state of marine reef keeping, I don't need a calcium reactor?
Maybe I'm wrong, but it seems to me you had tested calcium reactors in the past, which appeared in FAMA. While I'm willing to spend money purchasing a new CalPro, I was hoping you'd recommend other calcium reactors for me to consider. I prefer equipment rather than manually adding "calcium" daily, since I travel somewhat.
I'm not sure if any of the following parameters would influence the kind of reactor you'd recommend: My fish and corals are generally long-lived, with some corals reproducing in the 135 gallon, equipped with plenum system, according to your instructions. Aquarium lighting is by 4 timed MH 20K Starbursts. I dose with Kent Marine's Tech I once a week per instructions and also add a 1/2 tablespoon of Coral Vital daily (when I'm home). Water changes are done about every week, give or take a day or two. I use ozone and a Kent Marine's RO/DI unit. Any recommendations would be appreciated.
Walt Brodrick
PS: Since going the plenum route several years ago, I haven't had any microalgae problems. It made a difference in my staying with this great hobby. Thanks!!
Hi Walt,
Sounds like the system is doing well and who ever said plenum systems crash when they become a year old! I was just speaking with a reader whose plenum system is now eight years old and is in excellent condition!
Anyway, as for reactors, I would consider using MTC smaller calcium reactor, the Mini-Cal. I had that running on a larger system than yours and it did quite well.
Checkout my new website at www.saltcorner.com and let me know your thoughts,
Cheers,
Bob
Hi Bob,
Thanks for your quick reply. I just spent a few minutes looking over your website. I hate to use a trite phrase but, "it's awesome!" I'm going back and spend more time reading the articles and gawking at your fantastic aquariums, but I had to tell you first what a great service you're providing, by making your website available.
On a personal note, if it wasn't for your articles, especially on the plenum system, I'd be out of the hobby years ago. Before your articles appeared, I was about to admit failure in my fight against microalgae. It was frustrating. You've heard similar stories from others so I won't go through the details. Your articles came out at the right time, at least for me. Thanks to you, many of us are benefiting from your selflessness and knowledge. Bob, keep up the great work!
Thanks!!
Walt
Hi Walt,
Thanks for the kind words,
Bob
Dear Bob,
I have been reviewing your columns in my back issues of FAMA and decided to try to set up a saltwater tank with a live sand filter. I have years of experience with a variety of freshwater fishes, but have not taken the plunge into the marine world for one simple reason. I live overseas on an island in the Pacific, which has no support for saltwater hobbyists and minimal support for freshwater hobbyists. I can purchase small aquariums, powerheads, and air pumps, but not much more is available commercially. I want to set up a saltwater tank (about18 gallons) with a sump (about 50 gallons). A rubber type container with a lid will be used as the sump. What do you think about setting up a live sand plenum filter in the sump without any lighting? This will leave more room in the display tank. The water and everything else that goes in the tank will have to come from, you guessed it, the beach. Of course, I will need to check to ensure I don't violate any laws. Any additional advice that you offer would be appreciated. Thank you in advance for taking the time to reply.
Sincerely
Ray
Jejudo, Japan
Hi Ray,
Thanks for your email and as for the interconnected sump being used mainly as a biological live sand plenum-type filter (refugium), it should work nicely. And, keeping it somewhat in the dark should prevent unwanted cyanobacteria or microalgae from becoming a nuisance in this area. However, I would not seal the top of this rubber container with a tightly closed lid. You want good gas exchange and a simple aerator in this container would be quite useful.
I would also recommend placing some live rock or coral rubble in this 'sump' to provide additional biological filtration. Yet not too much as to block the majority of its sandbed surface. You may also want to consider some minor animal life in the sump area if this is to be a cool water system, such as crustaceans from the Island's surrounding waters. Maintain the sump area as needed, as basically it's no different than the main system. It's a small world by itself. Keep in mind it also needs good water movement, as does the main system
For appearance sake, the main system's bottom would only need a very shallow covering of sand, probably less than a quarter inch would suffice. Sounds like an interesting project.
Hope this helps and please keep me posted.
Bob
Dear Bob,
Over the past year you have blessed me with good reefkeeping advice, sound setup and maintenance practices for my tanks, and "extended your hand" in helping me purchase excellent equipment by offering unbiased reviews on many great products. For that and much more, I thank you.
I am writing particularly to give thanks for some advice you have given me recently on selecting an good skimmer. Well, the word "good" doesn't do this product justice. My Aerofoamer 824 skimmer came in the mail today, beautifully packaged and complete with detailed instructions and all the necessary parts in pristine condition. Assembly was a snap, taking only about 5 min. to assemble the four parts together. I really can't wait to fire it up!! Unfortunately, the rest of my tank is not ready yet so it will have to sit for a couple of weeks. Frank, the owner of the company, has also been helpful to me in planning the setup of my skimmer and sump. I have rarely received such excellent service from anyone, anywhere. You can surely tell that Frank really loves this hobby.
Anyway, my thanks to you for your advice. As always, you save me money.
Kind Regards,
Jeff
Hi Jeff,
Thanks for the feedback.
Bob
Dear Bob,
I have been operating an aquarium service in the LA area for the past ten years. The plenum filter system has seemed to work well with invert dominated tanks. My question is to what advantage could the plenum system be used in a fish only aquarium. Many of my clients enjoy large angels, tangs, eels and groupers. Housing these animals and processing their waste would need a large bio filter such as a wet/dry. Could you (or would you) use a plenum with a wet/dry?
Thank you,
Kim Koch
Hi Kim,
That's a good question and I can understand where you're coming from. It would seem reasonable to think filtration equipment such as trickle filters and fluid bed filters would be the best way to handle the bioload generated by large animals or in a heavily stocked fish-only system. Yet, that wisdom is now being rethought by some very knowledgeable folks!
The Oceanographic Museum of Monaco has a full-sized coral reef system called the "Lagoon of Sharks.' You can see an article about that system on my website at www.saltcorner.com. It features a coral reef on one side and a deepwater area on the other side for big predatory sharks and rays. This whole structure is two stories high and 33 feet by 30 feet wide and holds about 100,000 gallons. It is divided in half by an acrylic panel with each section separately filtered because they did not want the pollutants generated by the large animals to affect the more delicate invertebrate in the living coral display. However, each side is filtered by the Jaubert plenum method, with additional sand filters used on the large animal side. Both systems also receive a 1% natural seawater exchange hourly. Nitrate readings remain a little high on the large animal side, but 'its' anemones, clownfishes and cardinalfishes have reproduced and are forming large colonies. As for the living coral reef side and its more delicate inverts, its water quality remains perfect.
And, about two years ago I helped a shop called UK Marines set up their filtration system with very large plenums. In fact, it's 16 feet long and five feet wide. They have 1000's of gallons of fishes, corals, and live rock all filtered by their plenum system. And, their nitrate reading throughout their systems is usually barely readable! There's also an article about that store on my website. Prior to that, about three years ago, I did the same here in my home town with a shop called Angelfish Reef. Their system nitrate level was almost always 2 ppm or less.
But it should be kept in mind those plenum systems are dedicated systems with wide-open sandbed surfaces, and they work well! Yet, in your client's tanks, which contain a heavy fish-only load it would be more practicable to use trickle filters and/or fluid bed filters, which are easier to service than a sandbed. This is not to say the plenum method would not work, but in your line of work time is money. And you want to be in and out without spending too much time on each system.
Bob
Hello my friend,
You don't know me, but I tell my friends you are my mentor. I have read your columns since their conception in Marine Fish Monthly, which goes back over fifteen years, and now follow them in FAMA. And I thought you should have this feedback.
I have a 55 gallon plenum that has been on going for 5 (maybe 6) years now. It has been marvelous in performance. Algae is almost non existent, nitrates are, always have been, unmeasurable since it cycled. I also have a 75 gallon Berlin system that is 12 years old that is now coming down for replacement with a 180 gallon tank. This has been a reliable tank, but not like the plenum system!
Unfortunately, a few years ago I suffered some serious health problems, which as you can guess put a real load on my wife when it came to tank maintenance. The plenum system required very little maintenance, the Berlin, of course, a lot more. The plenum came through unscathed while the Berlin did not fare as well.
Now that I'm feeling better and am ready to move the Berlin system into the 180, I have a few questions. I want to use a remote plenum. You have written that you set up a 180 using a remote plenum. I have a 55 and a 75 gallon long that I can use for a remote plenum. Which one should I use? Do you have any diagrams, which show the best way to get water in and out of the remote plenum? Also I need to get water to the protein skimmer which I am considering using the sump for. In your new CD book you say to use 2 mm grain size sand. CaribSea has a product called 'reef sand special blend' which has some smaller grains like 1.5 to 2mm. Will this work ok? I will set the eggcrate grids on 1 inch PVC pipe and wrap them with fiberglass window screen. Any comments? What's your thoughts on using 1/2 live and 1/2 dead sand?
Thank you my friend for all the help you have given me and others over the years. Although we have never talked before, your guidance has always been there.
Grover Cannon
Eugene, OR
Hi Grover,
It does my heart good to see such honestly in one's mail, yet it saddened me greatly to hear about your health problems. I wish you the best future possible and I mean that from the bottom of my heart.
As for your questions, let me address first your question to place the plenum in an interconnected tank, i.e., auxiliary plenum system. This method has become widely accepted, as many aquarists simply do not like the look of a very deep bed in their main system. Not only has it resolved that issue, it is proving to be more easily maintained when not cluttered with live rock formations and various coral animals. My 180 gallon solar powered reef aquarium used a 60 gallon plenum tank under the main tank. However, that main tank had 27 fishes and was fed as many as six times a day. I found that size interconnected plenum system not capable of keeping nitrates below 5 ppm, as originally desired. Its nitrate stayed about 7 ppm. Therefore, it only seems reasonable to assume a slightly bigger plenum system would have reached that goal. Because of this personal experience, I now think the interconnected plenum system not be any smaller than half the size of the main tank, and therefore would recommend use of the 75 gallon tank.
I don't have a diagram showing how to do that, but can say the water from the main system should overflow a standpipe or overflow chamber and gravity feed into the lower plenum system. I used a SEN 350 located in the sump to return water to the main system. Where the water entered the main system I placed a control valve to regulate the amount of return flow. In fact, that control valve was the type found in RIO pump boxes and it worked well. Flow from your plenum system, if the 75 gallon tank is used, should be about half its volume, or about 40 gallons per hour, and that's the reason for the inline control valve. A somewhat more flow is also possible and feedback is showing that even higher flows work well. How high, still needs more input data, but would guess at this time your return flow could equal that of the remote tank.
When it comes to sand grain size, anything in the range of 1.0 mm and above to about 5 mm will work nicely. The 2.0 mm is an average size, and CaribSea does have sand that is somewhat larger than what you mention. Its their Seaflor Super Reef product, which I consider the best choice size wise. In fact, it now comes package 'live' and that helps shorten the initial cycling time. You could also simply use crushed coral, as that will also suffice size-wise.
And, as for half live and half dead sand, that's okay, but place the live sand on top. As for the plenum grid, it sounds like you have the right idea, but if any questions remain, ask before it gets cover with sand. Lets do it right the first time, but then your 55 has been doing great for five years, so it seems you understand the requirements.
Otherwise, appreciate your letter, enjoy and stay well.
Bob
Hi Bob,
I don't know if you keep records as you probably get 100's of emails, but about 6 months ago I emailed you about my new NNR set up. At any rate, I upsized from a 90 to a 250 gallon tank which was going to initially be a fish-only tank, and still is. I set it up so that I would be able to switch to a reef somewhere down the road, with just the addition of better lighting and maybe a calcium reactor.
I read your booklets and set up the NNR system as described. I have a plenum in the aquarium and about 120 pounds of Fiji live rock which is supported on a flow through grid just below the top of the sand. I also converted an old 50 gallon aquarium to a sump with a NNR sandbed. The sump is simply a flow through from the aquarium to a second sump, which houses my protein skimmer and feeds my main return pump.
The system has been up and running for about 6 months and so far things have been great. My nitrates have been below 10 ppm and everything else is exactly where I would like it to be. Unfortunately I have had to dismantle the sump with the NNR sandbed to replace one of the end pieces of glass that developed a small crack (the joys of saving money by using an old aquarium). While the filter was running I noticed that the bottom 3 to 4 inches of sand was a darker color with a black tint to it than the top inch or so.
When I dismantled the filter I noticed a faint but definite sulfur smell when I exposed the bottom 2" of sand. There was no smell from the filter before I exposed the bottom two inches of sand either while it was running or even when it was drained. I separated as much as possible the layers of sand. I have the sand from above the top screen in one container and the sand between the top screen and the plenum in another container. Both containers have the sand covered with salt water. I also took water samples from the water that drained from the plenum area and tested it along with the water from the main aquarium. The water from the plenum was virtually nitrate free while the main aquarium had about 5-10 ppm. The pH might have been slightly less in the plenum but everything else was the same as the main aquarium, i.e., zero nitrite and ammonia. There didn't appear to be any sediment in the plenum area other than the sediment from the sand that I didn't get rid of completely when I initially washed the sand before I placed it in the filter.
My questions are (finally you say)!
1. Is it natural to have the faint sulfur smell in the area of sand which isn't exposed to oxygen and should I be concerned about it. Is it possible that this could develop into something that might cause my tank to crash much like what can happen with undergravel filters.
2. My original plan was to replace the sand in the same relative layers without rinsing it at all. Now I am wondering if it should be washed thoroughly with fresh water before I replace it to eliminate the sulfur smell and start fresh again. I realize that this will destroy all the bacteria that have developed over the last 6 months, but the smell does concern me. The smell is fairly faint but I can notice it especially when I place my nose close to the sand.
3. If this isn't a normal occurrence how do I avoid it happening again? Actually, I would not even have been aware of it had I not had to replace the piece of glass. In a worst case scenario this might have been a disaster in the making and I would really like to avoid that in the future.
I look forward to your reply and want to thank you in advance for any advice you might offer me. I really appreciate your help.
Dave Lineker
Hi Dave,
Hundreds of emails per month is about right! And thanks for an interesting and well written letter about an area of concern many aquarists don't fully understand - the sulfur cycle. I've heard so many different positions on this subject that it's no wonder there is much confusion. Some aquarists think darker colored sand is the beginning of the end, others blame their existing problems on it, others say a particular method is the sole cause, etc. and etc.!
Actually, the process that causes some degree of hydrogen sulfide (H2S) is a 'very normal' happening in any type bed, especially those that exceed a few inches in depth and/or even shallower beds of very fine-grained substrate.
Let me begin by first explaining the sulfur - sulfate process, however, its going to get somewhat technical.
The sulfur process is actually a never-ending pathway or mechanism both in the wild and in the aquarium. It moves from sulfate to sulfide, then back to sulfate with the help of various types of bacteria. Dissimilatory Sulfate Reducing Bacteria (SRB), using excretion and decomposition produce sulfide. The resulting sulfide can be re-oxidize back to sulfate with the help of Colorless Sulfur Bacteria (CRB) and Purple Sulfur Bacteria (PSB). Again, this normally occurs in sandbeds deeper than a couple of inches and especially in fine grain beds. To what degree depends upon the depth of the bed, its physical grain size, and whether there is a plenum or the bed sits directly on the aquarium bottom.
Keep in mind that the activity of aerobic heterotrophic organisms in the upper sand level deplete oxygen, and fermentative organisms in this rich area of organic material provide the growth substances for the SRB. Whether in plenum-equipped aquaria, sandbeds directly on the aquarium bottom, or in the wild, the process is the same - the SRB reduce the sulfate to sulfide. In fact, the SRB move upward in the sand column at night to get more oxygen since the oxygen level in general decreases at night. Should there be some areas near the substrate surface with very little or no water movement, fish deaths could occur due to low dissolved oxygen in the area where they rest at night. This is another good reason to have adequate water movement in closed systems that utilize any type sandbeds.
As for sulfide in micro-areas where there is no oxygen, PSB will oxidize sulfide to sulfate provided there is light. Where there is excess oxygen, almost all sulfides will be oxidized back to harmless sulfate by CSB. Actually CSB has higher affinities for sulfide than PSB.
As I see it, the 'Chicken Little' attitude regarding H2S is on the fringe because the natural ecology of the sandbed is to maintain it and keep it from causing a harmful release unless stirred up mechanically. Actually, H2S has always been given a bad rap because the somewhat blackish coloration of the sediment was/is equated with a drastic, life-ending situation that was soon to occur. And often the filtration method was blamed, not the real cause of the situation. Which could simply be the placing of flat rocks on their flat sides directly on the sandbed surface, therefore blocking the penetration of oxygen. Or blocking the interface of sand and bulk water by allowing the bed material to cake-up and form solidified/concrete-like chunks.
To carry this thinking somewhat further, typically there's a natural need for sulfur bacteria in sandbeds, as they comprise several important microbial groups just under the sediment surface. They occupy much the same vertical profile and space the nitrogen bacteria do and they are linked to metabolism in the carbon cycle. In fact, sulfur bacteria are very much needed in the bio-geochemical pathways that are crucial to energy cycling and the equilibrium mechanism that produces balance in the closed environment.
Actually, sulfur 'metabolism and pathways' are not really a cycle, but more a process which can also tie up (store) excess carbon. When the nutrient flux is on the upswing, but metabolism is slow or at its limit, a natural storage effect occurs. Ideally there should be a portioned relationship with nitrogen, often referred to as the Redfield Ratio (C:N), which is about seven parts carbon to one part nitrogen. When an increased amount of carbon shifts the ratio, sulfur bacteria can temporarily store some of it, thereby buffering the flux. In the wild this has been linked to storage for future use, such as in spring algae blooms.
And, as an interesting side note, sulfur bacteria may be linked to the movement and use of phosphate. Classically, in numerous articles it has always been assumed that phosphorous released from sediments is an abiotic or kinetic process. In other words it happens physically, not biologically by microbial mediation. It now appears that phosphorous (including phosphate) under reduced oxygen conditions links ferric (iron) minerals to reduction thereby producing ferrous ions with a co-release of the phosphorous that is absorbed to the ferric mineral.
When the metabolism of bio-available carbon occurs, it in turn causes an increase in oxygen consumption and a concurrent reduction in the redox potential of the sediment. The iron then present in this environment reduces and in the process, phosphorous is released from coupled iron surfaces. Bear in mind that in reduced oxygen environments the electron acceptors between sulfur and iron are closely coupled, thereby making phosphorous release very possible. But don't get too depressed as some of this is designed for uptake into energy production components such as ATP. However, it is reasonable to assume that if equilibrium is shifted with abundant iron, carbon, sulfur ions and a redox that is shifting too far negative, the result would be a release large enough to override equilibrium and favor phosphorous users like algae. Instead of the gain being energy, phosphorous then goes to primary production of plant tissue. If so, one could assume that the use of iron additives and/or media rich in iron may be less than a good idea when it comes to maintaining an algae free environment.
To follow this line of thinking it might then be somewhat perilous to have a sandbed with a large stagnate area of sulfur-laden sand. A deep sandbed without a plenum is a good example as it has a highly favored location for anaerobic microbial mediation. This would equate to a larger carbon storage area of less productive anaerobes. A situation now more favored for phosphorous release than ATP production. In such a case, when sulfur bacteria decouple carbon from the carbon cycle for storage, iron may also accompany the mechanism to facilitate phosphorous release. A large carbon flux shifting the C:N ratio would facilitate this condition and the resulting reaction. This effect fits many case histories and observations in the aquarium where nitrogen nutrients and redox are at low levels but there are hair algae blooms on the substrate (rock or sand). An even worst example would be an iron rich, swamp-like mud-like sediment! And if so, methane could now enter the picture, which is a very possible situation that unfortunately many don't think about when very fine mud-like sediments are used.
Getting back to your situation, having a nitrate free plenum space in the sump tank indicates your plenum bed was not functioning correctly. It could be that the area under the screening was totally oxygen free (anaerobic), which is the cause of the darkening sand/H2S smell. Normally, a plenum system, because of its oxygen content in its bed and the plenum space itself, differs from that of the wild and that of deep beds directly on the aquarium bottom. However, if the pathways are blocked/clogged, it begins to function no different than deep beds directly on the aquarium bottom. In benthic sediments in the wild the chemical pathways are somewhat stagnated due to the lack of oxygen in deeper zones. However, with a plenum the aquarist has manufactured an area of considerable volume, which is in steady flux thanks to diffusion gradients. Even though plenum mechanics are fairly straightforward that doesn't mean they are always perfect. Sometimes the dividing screen, which isn't always needed, clogs with excess detritus and/or possibly some very fine sand - something below 1.0 mm. When that happens, H2S, because there is less diffusion and/or bioturbation, will depict its presence. Whether that is a growing problem or something the system will be able to naturally deal with in the long run, is an unknown as every system is different, just like people. Yet, most of the time, H2S is not released into the bulk water unless the sand is stirred. However, I would think about leaving the dividing screen out if there would not be any digging animals in the sump. And simply wash the sand with freshwater and reuse it as the bacteria species that will inhabit it in the future will be a different species than that which was living in the darken sand.
I question the need for a 'flow through grid just below the top surface of the sand' in the main system, as that may become a major obstruction to diffusion should that sand area become solidified. Precipitants and/or mats of bacteria can cause sand areas to become concrete-like. If you can't breakup those clumps of sand, the area under that hardened layer will become anaerobic and your nitrate level and possibly unwanted algae growth would increase, as would H2S increase. And, that will not be the fault of a plenum design!
Checkout my new website at www.saltcorner.com and hope this helps,
Bob
Dear Mr. Goemans,
I thoroughly enjoy your Sand Mail column in FAMA each Month. Thanks for always wonderful information. My question is unrelated to sand beds, but I turn to you with faith that with your experience you can provide some answers.
I have been using multi-socket power cords in the stand of my 125 gal reef tank. One recently burned out and I have to replace it. The problem is that all the multi-sockets and surge protectors I find say at least "not for wet or damp areas." Some, such as one model on sale at a pet shop, specifically state "Should not be used with aquariums." Even hardware stores' power tool 'built tough' extension cords say the same things. What's a fellow to do? Are these statements similar to "Don't fold baby stroller up with baby in it" as a way to protect the maker? Or, are these extension cords more sensitive to moisture? My tank stand is not wet, damp or moist. However, there is a sump down there, too, which may raise the humidity slightly above the normal room humidity. Would this have a negative impact on a multi-socket? I use GFIs.
I use three 6 or 7 socket cords. One with a 7' cord to reach the wall electric outlet (which also has a wave maker and heater, winter only, plugged in) with a chiller, small air pump (fresh air to the sump), and small light (so I can see better in there) on it and the two other cords. The second cord has a timer for my two VHO actinic lights and cooling fan, and another timer for the two daylight bulbs. The timers cover up most of the individual sockets and I can control the lights better on a separate switch. The third cord only has a wave maker and the water pump on it which allows easy on-off control when I am working in the tank or feeding.
Obviously, dripping/cascading water into any electric socket is bad. But, are manufacturers being overly cautious with their products by saying not to use them with aquariums? If a cord doesn't say that, does it mean that it could be used, or just that the maker hasn't gotten around to listing such factors? Are there sockets out there that are designed for aquarium use? I have seen the Natural Wave Timer, but don't need more wavemaking capability and just three additional sockets aren't enough.
Thanks in advance for any advice you can provide.
Harry Haley
Yorktown, Va.
Hi Harry,
Ever heard the term 'CYA?' Ever hear of 'Lawyers?' They go hand-in-hand!
Its not that these devices are more sensitive to water, it's just that water and electricity don't mix!
It probably goes without saying that one needs to figure out the total amount of electrical draw on a particular circuit before plugging in a lot of devices. Each home circuit is probably rated at 1500 watts and/or so many amps. You first need to know how many outlets in your home are on the circuit where you aquarium devices are plugged in. could be a total of 8 outlets. Could be there are other outlets on this circuit being used for a TV or other devices. Total up the consumption of all these devices and if at any one time they would exceed the rating of the circuit, something has to be taken out of service.
If you plug in devices requiring more than that, the wiring supplying that electricity will get hot. Yes, there's a certain amount of overage each circuit can draw before its tripped, but sometimes these circuit breakers or safety deices don't work and a fire results.
And, whether marked or not, all plugs at sensitive to moisture. And moisture condenses and if enough gets inside an electrical plug, there's going to be a short. Having a GIF circuit for your aquarium devices is the smart way to go!
And there are not generally available moisture proof sockets, however, they are probably available at a high price. Where, I'm not sure, but you could do an internet search. Possibly coating the socket with silicon might prevent moisture from entering - jus a thought.
Cheers,
Bob
Dear Bob,
I'm experiencing a hair algae problem and it is getting significantly worse day by day. Yesterday, I noticed I wasn't getting very much flow out of my powerheads. So I unstacked approximately 1/3 of my live rock to get to the powerheads. I learned that four of the intakes (I have seven powerheads in the tank) were totally stopped up with hair algae. The algae was loose and easily removed. In other words, it was not adhered to or stuck to the intakes. This makes me think the intakes vacuumed it from other areas within the tank. Regardless, I am certain the powerheads were helping distribute the hair algae throughout the tank. I also have a couple of pieces of live rock now beginning to grow hair algae between the crevices.
Yesterday, per instructions of my local dealer, I put 50 blue-legged reef hermits and 5 emerald crabs in the tank. Approximately a month ago, I also put an additional 75 red scarlet hermits in, yet they did not help the problem.
Last night, my local dealer who works out of his house and I must admit has an absolutely gorgeous 500 gallon tank, recommended cutting off all nutrient feeds except for a two-part calcium and alkalinity additive for at least two weeks and most likely three. He also recommended decreasing the metal halide lighting from eight hours per day to six.
I began following this recommendation plus did another 12 gallon water change last night. I have been doing weekly 12 gallon changes for months now. In addition to the hair algae, I have another phenomena occurring. Many of my corals are doing great and some, very poorly. My Acropora corals look very good but my Elegance coral, which used to be 8 inches across is now about 5 inches, and my Yellow Fiji leather coral, which used to be 7 inches across, is now approximately 3.5 inches. Therefore, I assume they are not eating enough or are missing key nutrients or lighting.
Last week, I had my ORP analyzed and it was 340. I though it should have been higher. I have less than 1 ppm nitrate, no phosphate, no silica, 3.8 alkalinity, and 430 ppm calcium. As for my pH, in the early morning its 8.0 - 8.1.
I was discussing my problems with a guy on the Internet earlier this week and he thinks my skimmer is part of my coral problems. This skimmer is very much oversized for my 75 gallon tank, however, it puts out billions of fine air bubbles. Each night when I get home from work many of my corals are covered with air bubbles. Some of the live rock is also covered. I use a turkey baster to blow the bubbles off, yet the Elegance coral and yellow Fiji lather coral have never been covered with bubbles. I did note last night that the Elegance had a large chunk of hair algae growing off the side of it. I removed it from the aquarium and brushed the algae off with a plastic brush.
The only other thing I should probably note is that I have been experiencing temperature problems for several months now. The temp is 77F when I leave for work in the mornings but around 81 - 81.7F when I get home at night. I have been placing four frozen 4 liter plastic coke bottles (filled with water and pre-frozen) a day in my sump to keep the temp in this range. If I don't the temp gets even higher. I have also put a 10 inch fan in my cabinet which now constantly blows air across the sump. I am considering purchasing a used chiller. My dealer has a 1/3 horsepower model that is about 2 years old. He is asking $300.00 for it. He was using it on his 150 gallon aquarium and since he has recently upgraded the aquarium to 500 gallons, he now wants a bigger chiller.
In my two years experience with corals, I have truly enjoyed them, but they can be a pain. I have studied, read, and tried to do the right things, but there are so many different opinions out there. I have learned a lot from you (for which I am very thankful) and have purchased and read all your books. Your book on controlling marine algae has been a great help, but I am not over the hump yet. Additionally, I simply have a hard time understanding why I am having hair algae problems. I never had it before and I haven't introduced any new fish in the system or corals for over 6 months.
As always, thanks for your time and assistance.
Danny Key
England
Dear Danny,
Hair algae is a major problem when it gets a foothold. Even though your present water parameters appear fine, unforeseen conditions when you first set up this aquarium and on-going questionable husbandry practices are now beginning to manifest themselves in the form of unwanted algae. Do I have a magic cure? No. Can it be overcome? Yes, but you have to be willing and able to apply the labor needed to overcome the problem.
Let me explain where the turns in the road lie in many of these cases so those that may also read this don't make the same mistakes.
Whatever the system, fish-only or reef, its on-going health and water quality have a lot to do with those bacteria that live in the dark reaches of the system. Too many aquarists give only the nitrification process some thought and surmise that if ammonia is oxidized to nitrite, then nitrate, that takes care of the hazardous animal wastes. And many establishing reef aquariums are still being lead to believe lots of live rock will rid the aquarium of the end product of that nitrification cycle - nitrate. Nevertheless, many years of research has shown there is more to it and if what has now been learned is not applied, unwanted forms of algae can possibly gain a foothold and ruin a perfectly nice looking system somewhere down the line.
Keep in mind almost anyone can have a successful tank if they spend the time and money on it to keep it looking good! However, one successful tank does not make a 'guru!' If your dealer had fifty years of experience and a continuous chain of successful client systems, I would be at his door wanting to checkout his method. And, if I were to sell products from my home, my home aquarium would always be at its best no matter how much time and money it took to do so. (I'm just saying here don't judge his expertise by one aquarium. Evaluate his recommendations before jumping in so to speak.)
Anyway, the goal in setting up a new system is often impacted by what the system should 'look' like and how fast it can be accomplished. Understandable, but somewhat misguided in my opinion as it's putting the cart in front of the horse. Unless more thought is first given to the things we can't generally see, such as microbial efficiency/natural pathways, closed systems can not continue to operate as does Mother Nature in the wild, at least not without much additional cost in time and money. It may look great for a while, but Mother Nature can be seriously irritated once her pathways become dead ends.
There is now scientific evidence that more forethought needs to be applied to the microbial processes taking place in closed systems. If we better understand how, why and where certain type of bacteria perform, its very possible the closed system will be more 'natural-like' in the long run. One of the many things discussed in my CD book 'The New Wave' is the fact that if the 'area' that houses inefficient bacteria (such as found in the depths of a deep sandbed directly on the aquarium bottom and inside that of live rock) become greater in volume than the area housing efficient bacteria, the system 'will' become nutrient rich. That's just plain commonsense, but it took about six years of research to gather the facts and evaluate. And, its only one part of many interesting new views discussed in the CD. And I should note that Martin Moe Jr. and Dr. Jean Jaubert were impressed with the CD's content!
Anyway, when these inefficient areas produce more nitrogen based products than what can be used by those bacteria in efficient areas or exported, the aquarium will suffer a war with algae sooner or later! And, very efficient skimmers and water changes are not going to cure the problem. They may postpone it or reduce the intensity of the problem, but they don't cure the root cause.
Research has shown that anaerobic areas generate an ample supply of ammonium, which is the favorite algae nutrient. Remember, nitrate is only reduced to ammonium, no further in anaerobic areas. Yes, nitrate is reduced and when the bulk water is tested, low nitrate levels appear to be under control because of the denitrification process in deep sand and inside rock. But that can be somewhat misleading because in anaerobic areas, nitrate is only reduced to ammonium (a nitrogen compound), no further. Fact, not fiction! However, in anoxic areas, nitrate is fully broken down/oxidized. Therefore, anything much over an inch or two of sand and/or the over abundance of live rock is the perfect breeding ground for the ideal alga nutrient. And, this production of ammonium is not visible on our test kits, so the average aquarist doesn't see it. But the formation of algae in the aquarium is in part the result of this ammonium production, as algae is the physical incorporation of nitrogen compounds! Many aquarists also fail to adequately control phosphate. So it should be clear that minimizing anaerobic areas in the aquarium and the on-going control from the start of the aquarium where phosphate is concerned, is essential in preventing unwanted growths of algae somewhere down the line.
Even though you say zero phosphate, I doubt that very much. Anything over 0.015 mg/l is sufficient to get an algae spore growing. Unfortunately almost all aquarium test kits only go as low as 0.05 mg/l, and even that is doubtful because aquarium reagents are not very accurate. Only the Merck Phosphate Test kit #1.14445.00001 goes to 0.015 and below, and that kit is difficult to get besides costing about $65. But if you're serious about this hobby, that kit is well worth the money!
And, unfortunately, many aquarists don't bother with phosphate removing compounds until they either see algae growing or until they see a significant reading on a test kit. That's like closing the barn doors after the horses have fled! Phosphate production is a normal microbial process and its abundance depends upon many factors. But it's inescapable and actually a needed process if anything in the aquarium is going to live. It's the over abundance of the compound that needs our attention. That means using a quality phosphate removing product from the get-go and keeping it replaced often, as its our cheapest anti-algae insurance! Furthermore, it's the 'iron' based phosphate removing products that you want to concentrate on using, such as the Marc Weiss Phosphate+Silicate Magnet, or the new ROWAphos product from the U.K. There are also some iron impregnated filter pads which are also excellent.
As for adding dozens of hermit crabs, which do not export their wastes, they simply make aquarium keeping unnecessarily more expensive and do not resolve the root cause! I had ten hermits in my past 180 gallon system and considered that about five too many! The use, or should I say the misuse of hermit crabs is also discussed in my CD book.
Pyramids or walls of rock, or covering more than 25% of the sandbed surface with rock is also a negative as it provides places for detritus to collect or sandbed areas that can't be cleaned/vacuumed. Somewhere down the line this adds unwanted nutrients/breeding ground for parameters that distract from the wellbeing of the environment as a whole. Now think about your powerheads, they are near some detritus filled substrate (how deep that is I don't know) where ammonium from the nearby rock and substrate is very possibly leaching into the surrounding water and being pulled towards the powerheads. A perfect place for hair algae to grow. And once growing, this cyanobacteria (yes hair algae is a cyanobacteria) needs little or no light! So why cut back on lighting? That's another subject covered in the CD.
Keep in mind ammonium is the key plant nutrient and phosphate supplies the energy to get it going. Those two ingredients are your root problem. As for ridding the aquarium of hair algae at this stage with herbivores, it's not out of the question if growth has not proceeded too far. Yet, hermit crabs would not generally be part of that solution as they are not going to consume tree-like growths. The common sea hare 'Aplysia ,dactylomela' feeds on algae of all types. Also the Florida Sea Slug/Lettuce Slug, Tridacia crispata, is fond of Bryopsis, a bushy form of hair algae. Yet their waste products need to be accessible/vacuumed out so it doesn't degrade and become a source of nutrients. As for weekly water changes, it has no bearing on this situation, so that's a total waste of money.
You're at a stage where an honest assessment of the present system is needed. Do anaerobic areas in the system have a greater volume than anoxic areas? If so, how best can that be resolved? - Redistribute some rock, remove some rock and sand, vacuum more often, and/or have a greater sandbed surface that is reachable for maintenance. Also, reassess the use of certain additives, use a quality brand phosphate remover and change it often, hand remove 'any' hair algae seen as often as needed. Keep using the skimmer, however, stop the flow of fine bubbles entering the aquarium. Contact the maker and resolve the problem. Maybe the skimmer effluent could be flowed through a sponge or enter some kind of diffuser area where the bubbles have a chance of surfacing before the water flows into the aquarium. And, don't change your lighting photoperiod, as the animals needing light have become use to that time period.
And I should add, you say you had the ORP analyzed. Actually 340 is not shabby, and if a water sample was removed and taken to a store, it would have lost some of its oxygen content and would be lower than what was in your aquarium. Also, don't use any of those algae killing additives, as 'some' algae types in the system is a sign of a very healthy system and quite beneficial. And remember, zooxanthellae are alga cells! These so-called algae eliminating additives are not in the best interest of aquarists!
I also don't know why some people think some corals are starving if they temporary shrink. Sometimes the opposite is true. They shrink because they no longer need to extend to capture more light or foodstuffs as what they have currently are sufficient. Sometimes shrinking is a normal procedure, especially for leather corals that use the process to remove algae/slime that has collected on their surfaces. When the coral resumes its original shape/size, the coating of slime/algae flakes off and is washed away by wave action. I think its far too early to assume the two corals mention have a problem. And, those two corals do not prefer direct metal halide light, as the Elegance comes from turbid waters and the yellow leather seems to prefer somewhat indirect, yet strong lighting.
Also, once algae begin growing on the coral skeleton, the coral animal (tissue) often recedes, as it can't compete with the intruding/spreading algae. Since the animal can not move to another clean site it often wastes away and the algae uses the nutrients from the decaying animal tissue as a food source.
I keep preaching the commonsense associated with microbially balanced aquariums. I'm not saying this always guarantees a perfect aquarium environment, however, it does give Mother Nature a fighting chance to be in control of her own destiny. And, I must add that I find microbes more predicable than infauna, therefore I rely more heavily upon bacteria than infauna to provide system balance. The problem with infauna is that it's impossible to tell what worms and/or crustaceans are accomplishing in the sandbed - simply guesswork! But not so with bacteria! And if the system is constructed with this in mind, Mother Nature usually does an admirable job. Hope this helps,
Bob
Dear Bob:
I saw your presentation at the IMAC conference in Chicago, and really enjoyed it. I agree on many of your statements about all reef aquariums being different, and that they require different levels of maintenance. Your column in FAMA has taken about a great turn in representing natural filtration methods for reef aquariums. I feel that these methods are the future of our hobby, and are responsible for our increased success with many of the species that have been so difficult to maintain in the past. However, the position that you have taken in your answer in the July, 2003 issue of FAMA, really surprised me.
Sand Mail is a column which "is dedicated to those aquarists interested in using more natural filtration techniques." I feel that your response was one that would have been given for advice 10 years ago, and is taking us back to a less productive time in our hobby.
Since then, we have made great strides in learning about ecosystems and the importance of "infauna" in our sandbeds, refugiums and within our live rock structures. Dr. Ron Shimek also spoke at the IMAC, and provided us with some valuable information on the biology of these organisms, along with the "Detritus Cycle". The most important lesson that I learned from his presentation, was the fact that organisms only utilize 10% of the food that they ingest, which makes these micro-organisms especially important in a closed system. If they are not present, this left over "food" or detritus, will remain on the rocks and within the sandbed where it decays. This does result in higher levels of nitrates and phosphates, and ultimately algae problems.
A well balanced reef aquarium, is one that does not require a large amount of maintenance, nor vacuuming of the sand. You stated, "As for adding dozens of hermit crabs, which do not export their wastes, they simply make aquarium keeping unnecessarily more expensive and do not resolve the root cause!" Again, going back to the "Detritus Cycle", crabs and like organisms are part of this cycle, and their wastes should be consumed by the copepods, amphipods, and other live sand organisms. However, these organisms will not be in any number to handle this waste if they are continually vacuumed out of the system.
I have proven on many reef systems, that mechanical filtration raises the overall nitrate and phosphate levels of the system. Instead of the particulate matter being consumed by the micro-fauna, this matter is trapped in an area of the filtration that has constant water flow. From the instant that this matter is trapped, it will begin decaying. I feel that vacuuming the substrate, periodically, will have the same effect on the overall nutrient level of the system. This is due to the lack of this micro-fauna, and the resulting deterioration of the left over wastes.
One last point on the lack of micro-fauna and its effects on the nutrient levels within a reef aquarium. All healthy reef aquariums are very difficult to remove any decaying animals from. It is these small crustaceans and worms that are responsible for doing the final cleanup in the event of loosing a fish, invertebrate, or any left over food. If they are not present, I think that these systems would experience much greater fluctuations in the water parameters than would be seen in a balanced system.
Among all of the advancements that have been made in this hobby over the past 20 years, I believe that the nutritional requirements of invertebrates and corals will prove to be one of the biggest. Eric Borneman recently completed a series of articles on the Advanced Aquarist Online Magazine, which outlined the nutritional requirements of various types of corals and invertebrates. He stated in one of these articles that nutrition in the form of phyto and zooplankton along with water movement are more important than lighting levels for the health and growth of SPS corals!
Keeping an open mind, and following all of the articles, it makes sense. There is a reason that with all of our knowledge and technology that we do not experience mass spawning of corals in our captive environments. I think that he is on to something. Other authors have explained the energy taxes in invertebrates, and that photosynthesis can not provide a coral with 100% of its daily caloric intake. They need food. If they do not have food, they will not flourish, and certainly will not breed! The food that they need are bred and reared in our sand beds, live rock and refugiums. The larger the refugium, the more live rock and macro algae, equals more food for the corals and more organisms to clean up the mess, resulting in decreased nutrient levels, and healthier corals and invertebrates.
I certainly did not send this e-mail to offend you in any way, and I hope that you didn't take it so. I am certainly not an expert, and I have followed and learned from your work for many years. Keep up the good work, and I hope that I can attend another one of your presentations in the future. Thanks.
Sincerely,
Chuck Wrobel
Hi Chuck,
Thanks for your well-written letter and I must agree that there is a need for zoo and phytoplankton in our aquaria, especially reef systems. In fact, checkout the Liquid Life ad on my website (www.saltcorner.com) as that product is a reef keepers answer to the phytoplankton need!
As to my answer about hermit crabs, what many aquarists don't realize is that they also eat the very bacteria that is needed to start breaking down the detritus that tends to accumulated on the substrate surface. I'm not against their use, however, want to simply say that an over abundance of them is not conducive to maintaining a balanced system. If you have the opportunity to read my CD book titled "The New Wave" it will go into more detail about the interconnected processes in the substrate and its connection with the bulk water.
And as for vacuuming, it should be used sensibly. Would you not ever dust your house in the hope that dust mites would consume all the dust! Again, each system needs a sensible level of maintenance/husbandry, and that does include a sensible amount of vacuuming.
Also, respectfully, I have to wonder about the people who quote how certain infauna operate in the wild and then tie it directly to the closed system. Yes, there are certain infauna that do accomplish certain activities, yet to say they are evenly plying the depths of your sandbed and performing the same activities as in the wild, is far from accurate. I can predict where certain kinds of bacteria will live, but can't even venture a guess as to where certain worms and crustaceans (infauna) may be tunneling!
Cheers,
Bob
Dear Bob,
I have enjoyed & learned a lot from reading your Sand Mail in FAMA magazine. I have a serious problem with nitrate & hope you could give me some advice.
I have a 29gal marine tank set up in July 2001. It started with an Under Gravel Filter recommended by my LFS for my FO tank. The UGF is constructed similarly to your described Plenum system with eggcrate as support for the horizontal grid with 3" aragonite sand. The air-lift tube is connected to a powerhead. The only info I lack of is the size of the sand. I have slowly upgraded it by adding an addition filter & skimmer. I've also added 20 lbs of LR on top of my 20lb base rock in August 2002. During all of this time I was not aware of the nitrate (NO3) becoming an issue. It wasn't until last December 2002 when a Hair algae boom began that I came to realize I had a NO3 problem. Using a Tetra NO3 test kit, I have a reading of 100 mg/l. After much research, I realized that my UGF and/or canister filter is the culprit.
I have immediately performed 25% water change 6 times in 6 weeks. 1st water change was on 5th January 2003. And on the 7th time, 16th Feb 2003, I have performed 60% water change. But the NO3 reading still remained 100 mg/l. My LFS used 2 types of test kit & the reading was the same.
My question is, can I disconnect the Powerhead from the air-lift tube & would my UGF automatically become a Plenum System?
My current system: UGF with 3" sand run by a powerhead, 1 Ehiem 2028 Canister, 1 Red Sea Prizm Skimmer, 1 add'l powerhead for circulation, 1 UV sterilizer, 1 x 2ft ZooMed Actinic Blue Fluorescent, 1 x 2ft ZooMed 10,000k Fluorescent.
My Fish stock: 1 Long Nose Hawkfish, 1 Six-line Wrasse, 1 Blue Damsel, 1 Maroon Clown, 1 Lawnmover Blenny, and 1 Yellow Tang.
My Coral stock: 1 Brown Button, 1 Green Star Polyps, 1 Hairy Mushroom, 1 Brown Mushroom, 1 Finger Leather, 1 Leather Coral, 4 Feather Duster Tubeworms.
Last reading on 16/2/03: Temp 80F, SG 1.022, pH 8.2, dKH 9, NH4 0, NO2 0, NO3 100.
Ehiem Canister Media (top to bottom): Poly Filter, Chemi Pure Carbon, Ehiem Ehfisubstrat, Seachem De-Nitrate (added on 26/01/03), Coarse Filter pad, Fine filter pad.
Thank you for any advice you can provide me.
Best regards,
Vincent
Singapore
Hi Vincent,
If you like the column, checkout my website at www.saltcorner.com!
Thanks for your letter, and there are two different methods for reading nitrate. Some nitrate test kits measure the "nitrate ion" and others measure "nitrate nitrogen." Nitrate is a compound or combination of elements. One molecule of nitrate is composed of one nitrogen atom and three oxygen atoms. Since the atomic weight of nitrogen is 14.01 and the atomic weight of one oxygen atom is 16, the weight of one nitrate molecule equals 62.01, or 14.01 + 16 + 16 + 16. Therefore the test kit that reads the nitrate molecule (the Tetra Kit) will show a reading 4.4 times higher than a test kit that reads nitrate-nitrogen. And nitrate-nitrogen is the more correct reading. That means your real nitrate reading was slightly less than 25 ppm. Still too high though.
It would be very helpful to read my Water Quality Booklet, mentioned on my 'Bob's Books' page. And, I should note that water changes are a waste of money when it comes to reducing nitrate, as the nitrate sequestered inside live rock and in the sandbed will simply flow back into the bulk water within a day or two after the water change.
Your fish load, and therefore the food fed to support them, is more than what a microbially balanced system can handle. Reducing the fish load may help control the nitrate level in the future. As for the canister filter, I would cut the Poly-Filter into small pieces and place it and the activated carbon in the canister filter. Adding more areas for nitrification only adds to the nitrate level. As for the de-nitrate product, I would place that where there's no forced water through it, as the oxygen in the forced water will reduce its efficiency.
And, the UGF may act like a plenum and help reduce nitrate level, however, it is in no way comparable to that of a plenum grid which basically has a much more 'open' surface area. UGF plates have openings probably making up about 25% of their surface area, whereas plenum grids have about 98% of their surface open for diffusion. I think you get the message. But, in your case you can try it and see where it goes. Hope this helps, Bob