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 have read your articles about the remote plenum set-up you have used in your 180 gallon reef in your office. You said your old 125 gallon reef with a plenum was so efficient the nitrates were always zero, and you wanted to have a new system that would keep nitrates just slightly above the zero mark for the benefit of some soft corals and mushrooms. I was wondering if you set the plenum up with a slightly 'shallower' depth of sand, say 3 - 3.5 inches, would that accomplish the same goal of a "less efficient" system? I have written you several times before, and my plan keeps changing. I have a large tank that was given to me several years ago and have always planned on making it a fish-only tank, but have now decided to make it my new reef. It is about 225 gallons (84 long x 28 high x 23 deep).
Since it is so tall, I thought it would be a fine thing to have the plenum/NNR set up, which would bring the water depth to about 23 inches. I could still set it up with a remote plenum, but was interested in your opinion. I feel like the remote plenum system would be great, but then I would have to find a tank, or get one made to fit under my stand, which would take up most of the space and more of my budget. I plan to add a calcium reactor as soon as I can. My main goal for my new tank is to keep SPS corals (after a proper break-in period), so it may be better to have the plenum at full depth to keep zero nitrates. I am also very interested in clams and leather corals, which would all appreciate a higher nitrate level. I really value your opinion.
Thanks again,
Sonny Stokes
Hi Sonny,
A shallower bed 'may' accomplish a somewhat more nutrient rich end result, however, that would depend upon the overall bioload of the system. And yes, your high tank with a plenum would provide a more workable depth for maintaining the lower reaches of the tank. Just keep in mind the need to keep the sandbed surface as open as possible, as it is the 'gateway' to the valuable microbial processes in its lower depths. The more live rock, the more it becomes difficult to keep the sandbed surface clean and of course, to monitor for possible sand binding. Having a mostly unimpeded sandbed surface and of course, proper size sand grains for diffusion, is the key to plenum efficiency.
Keeping nitrates low as mentioned in my previous articles is important, however, so is the phosphate level. Good sps growth can be expected when alkalinity is in the 3.5 to 4.0 meq/l range, calcium is between 380 to 430 ppm and phosphate level is below 0.05 ppm, preferably under 0.015 ppm. So, when it comes to good sps growth the combination of a plenum system, calcium reactor and an excellent phosphate remover are principal players, besides quality lighting and water movement. Sounds like you are getting your game plan focused.
Enjoy,
Bob
Hi Bob,
You helped me out some time back so I thought I'd ask you a couple of more questions. First let me say that I have all of your four booklets and look forward to "Sand-Mail" every month.
Around the end of 2000 I set up two tanks with plenums, a 37 and a 125. Both are 24" tall so I still have a good water height. I built the plenums exactly to your specs. Two 2" layers of sand separated by doubled window screen. Thank God for that because my first question has to do with a now mature female tomato clown who has taken it upon herself to dig for China. I believe the pair is going to spawn soon, she has built a nesting area and exposed the dividing screen, a circle about three inches across. Is this going to have an adverse effect on the plenum?
Next, after about one year I had terrible algae problems in both tanks. I know there are many factors but I just couldn't stand how dirty the sand was when I poked around in there. Is it supposed to look like that? I vacuumed the entire upper sand layer in both tanks in January and both have been very clean and pretty much algae free ever since. Did I do the right thing? (seems like it) It was a major chore to do the 125 and I wouldn't want to have to do it again, not even yearly. Had to remove all fish, corals and 100+ pounds of rock!
Final question: The aragonite has settled/packed/dissolved into a total depth of only 2.5". Do I need to build it back up? Can I do this simply by adding more right on top, perhaps a little at a time?
I know you are a busy guy but if you get a chance I would appreciate your advice. Thanks in advance,
David.
Hi David,
I do have to question why you placed two sheets of screening midway in the bed, as one would have been sufficient. As for your questions, the clownfish is allowing slightly more oxygen into the surrounding area, which increases the amount of nitrate being produced in those areas and of course, decreases the amount of efficient denitrification in some adjacent areas. Yet, I doubt its enough to affect the entire system and/or the plenum space itself since there remains about two inches of sand above the plenum space. If anything, there might be a slight rise in nitrate level, but that should pass once the depression closes.
I recommend that it's necessary to vacuum the bed surface once a month. Those who say never vacuum are incorrect - would you not ever dust your house!
And the depth question is yes, you have to add new aragonite when things start to look a little lower than a 4 inch bed. I have dumped some rinsed aragonite through a length of PVC pipe to various areas and then raked it with a homemade long handled acrylic rake to spread it out. Worked for me!
Hope this helps,
Bob
Dear Mr. Goemans,
I am in the process of starting up a 75 gallon reef tank and I am wondering if you could please answer a few questions. I have been trying to do as much research before starting and have read your booklet 'Live Sand Secrets' as well as John H. Tullock's Natural Reef Aquariums. There are a few points that I am unsure of when starting the system, especially when dealing with the plenum. You recommend using aragonite in the first 1 - 2 inches where Tullock indicates that it may eventually turn into chunks of concrete. I understand that you recommend using a dull knife blade to occasionally run through the sandbed, but can you get down far enough in the bed (through the screen) to break up the lower level?
Also, Tullock recommends using enough ammonium chloride solution to give 3.0 ppm on an ammonia test kit when the live sand is first added. I am assuming that he is attempting to help in the nitrogen cycle before any live rock and sea life are added. You recommend using a starter culture made for aquarium. Is this essentially doing the same thing?
Finally, several months ago you wrote about calcium reactors in your monthly Sand Mail. Could you please recommend one for me for my size tank.
Thank you for all your help and time.
Jason Isely
Plains, PA
Hi Jason,
Thanks for your letter. I have yet to see clumping under the dividing screen, however, it may occur but am not yet aware of it. Usually, its something brought on by either improper dosing of calcium and buffer additives where excesses precipitate and bind soft substrate particles together or fast forming bacterial colonies, especially in the upper layers. Binding always seems to appear to take place from the surfaces grains downward, therefore, it's why I recommend checking the substrate at least monthly. Whichever is the cause, ongoing substrate surveillance is necessary, whether it is in a plenum system or a deep bed (DSB) directly on the aquarium bottom as I've experienced binding in both types of beds.
Furthermore, the dividing screen can be encompassed somewhat in the formation of these clumps if the condition becomes prevalent. Not using a dividing screen is becoming more popular as is an interconnected auxiliary plenum system.
As for aragonite, it's one of the best substrates for reef systems, yet other forms of calcium carbonate can be used, e.g., crushed coral. The most important aspect of substrate material used for plenum systems is its grain size. And it's not necessary to use different types or grain size material to make the bed. One type of material, with a grain size of about 2 - 4 mm, will result in a bed having excellent diffusion capabilities.
The use of ammonia chloride is what's termed the 'inorganic' approach to establishing the nitrification cycle. It works well, however, nothing alive can be placed in the aquarium while the system is cycling. So that delays putting anything alive in the system for about four weeks. Generally, most hobbyists use the 'organic' approach, which includes the use of some live rock/live sand to supply the needed bacteria. If the inorganic approach was used with live rock, it would kill much of anything living on or in it.
Of all the helpful starting cultures that I've used for beginning new systems , I've found the Marc Weiss Bacter-Vital one of the best. This product appears to do more than just hasten bacteria growth, as it is my understanding it also helps balance the nitrogen/carbon ratio in the new system. This is extremely important to beginning with a balanced microbial system. Because of this it's often my choice as a starter product in my tanks and client systems.
As for a calcium reactor, I have suggested some brands in my return letter that I have personally have excellent results with.
Hope this helps,
Bob
Hi Bob,
I just finished reading your booklet "Protein Skimming & Activated Carbon Secrets". It was very informative and really helped me to understand both topics. I would like to take you up on your offer for advice on what brand and size of protein skimmer to purchase for a tank I am setting up.
My name is Nick Cavagnaro and I work as an exhibit designer and fabricator for the East Bay Regional Park District in Oakland, CA. The system I am setting up is a 700 gallon cold (61º) marine tank with local fish from the San Francisco Bay and will be the center piece of our Crab Cove Visitor Center in Alameda. I have some experience with a Red Sea Berlin power skimmer which is part of a 200 gallon tank system, also cold marine. I have this skimmer located in the sump where it draws water that has been run through a prefilter and a large bio-ball trickle filter.
I am asking for your recommendations on a downdraft or high speed aeration skimmer that would be appropriate for this 700 gallon system.
Thanks
Nick
Hi Nick,
Thanks for your mail, and checkout my website at www.saltcorner.com.
As for a skimmer, there are three companies that come to mind that not only make fine equipment, but have models that will handle a 700 gallon system. They are: AquaC, Reef Concepts and A.E. Technology Inc. Both AquaC and Reef Concepts can be viewed and linked to by visiting my site. They are on the Advertiser Page. As for AE, they are the first to make the downdraft models, and their info is listed below.
A.E. Technology Inc., RR1 Box 127, Poughquag, NY 12570, fax (845) 227-2812, (845) 838-9044, superskim@aol.com
You could not go wrong with any of these three companies,
Cheers,
Bob
Hi Bob
I've read a fair amount of your material and other people's views on the biomechanisms of what is happening within a plenum sand bed. It seems that not very much is known about actual mass transfer rates within the sand bed and I guess non-intrusive measurements for this are difficult and expensive to make. I'm a Ph.D. chemical engineer familiar with fluid mechanics, adsorption mechanisms and bio and pharmacokinetics - are there any major review literature papers that you can steer me towards?
Secondly - I am an amateur marine hobbyist with 2 years experience. I have some issues with my tank which I have been discussing with others and had the following reply from Scott at Wetwebmedia. (The bulk of the email is my text, Scott's comments are denoted
Thirdly, the presence of dissolved oxygen in the plenum does seem very counterintuitive (as detailed in your article in Jan 03 FAMA). Surely there has been an argument made by the bed having defects and there being a route for bulk liquid carrying liquid into the plenum but then I suppose this would not then explain why this area has a higher concentration of NO3 and other compounds than the rest of the aquarium water. How certain are the experimental measurements for the dissolved oxygen(DO)?
Regards
Geoff Purdom
Here's the web thread-
"I have some high Nitrate (80mg/l) and phosphate (3mg/l) problems in a 24 month 80 gallon set up. The setup gets a 5-10% water change on a weekly basis and is stable with a medium/high load of eight fish, two shrimp and a blue lobster. I tried to introduce an anemone, but it never fully open and unfortunately starved. I also have a bubble algae problem.
The set up is in two tanks, a 55 gallon which cascades its water to a 30 gallon tank which then returns to a wet/dry sump in the basement with a protein skimmer, mechanical filter, carbon, heater, UV then back to the 55 gallon tank.
My questions are:
1. Will I realistically be able to get phosphate down to a reasonable level for anemones and reduced algae? What should I aim for and will aluminum oxide be the most economic route. The phosphate comes presumably from accumulation from food.
<Well, ideally, you want to shoot for 0.05mg/l on phosphate, and less than 10 mg/l nitrate, if you can. I think it is certainly possible to lower phosphate in your system. I think there is certainly some phosphate coming from food, but there is also probably some phosphate in your source water. If you aren't using one already, you should look into an RO/DI unit, which can help you start off with more pure water. Another thought is that the mechanical filter which you are using needs to be cleaned (or have the media contained within it changed) more often (maybe twice a week). High nitrate and phosphate are definitely signs of nutrient accumulation. Attacking both together is possible. Your goal here should be to maximize nutrient export mechanisms. Your water change schedule is good; you may even want to try 2 smaller (5%) changes per week, to dilute the nutrients before they have a chance to accumulate. Also, try to really adjust your skimmer until it yields at least a couple of cups of dark yucky skimmate a week. It may take a fair amount of tweaking, but it is possible to get good results if you work with it. I'd employ extra chemical filtration media, such as Poly-Filter (my personal favorite). This stuff really works! Make sure that you are using a high-grade, phosphate-free carbon, and change it regularly. Another though would be to employ macroalgae, such as Chaetomorpha, Gracilaria, or Halimeda, and harvest them regularly. They will utilize many of the same nutrients that your nuisance algae are and they will ultimately beat out the lower algae. Harvesting them essentially removes nutrients from the system directly...yep- it works>
2. I have a tee'd off connection from the wet/dry to a 80 gallon rubberware container which will act as a plenum or it could be a refugium, and new sump. The water will be pumped back to the wet/dry on a recycle loop. I am planning on using 160 pounds of aragonite, coarse coral mix as a 4-5 inch bed over a 1 inch plenum space.
<Well, a plenum is a very useful tool if constructed correctly. It does require specific void space, particle size, etc, so do read up carefully if you plan on pursuing a plenum setup. Don't deviate from the established methods for constructing plenums - the techniques and guidelines were developed after a great deal of research. Check out Bob Goemans' web site (www.saltcorner.com) for much more on plenums. Bob is the authority on this system in the U.S. and can really give some great input! If you opt for a remote deep sand bed without a plenum, try a fine, oolitic aragonite like Carib Sea's Aragamax Sugar-Fine sand, and shoot for 4 inches or more.>
I have read that the plenum relies upon slight convective currents to effect as large an anoxic denitrifying layer as possible. Also since the sump/plenum is in my basement I am concerned about temperature control. I figure that I will put 30feet of 150W heating cable under the aragonite to deal with heating needs and achieve some convective mixing through the aragonite bed. Do you think this will work - will it be beneficial?
<To be quite honest with you, I have not seen this done before. It is an interesting idea, but I'm not sure whether or not it is worth the effort. I'd really encourage you to contact Bob Goemans on this one!>
The reason I started thinking of the cable heater is that the plenum will be in my basement which is about 40degF at the moment and only 50 -55 in summer. I live in New England. I figured that the rubberware tank itself (even although it will be insulated) would need some degree of heating and then subsequent small power head or air lift to get some recirculation.
<Absolutely...I agree.>
However this would NOT help the maintenance of temperature within the aragonite bed which would depend upon conduction for its heat from the main liquid bulk. Next I figure that the microbiological rates are probably favored by maintaining a reasonably high temperature 80degF. Therefore I have to find someway to keep the substrate at 80deg.
<Very logical approach.>
Cable heating is used here and there for encouraging plant growth in non-marine aquariums and this suggested to me what might work as a possible solution together with enhancing some flow through the sand bed. All the reading I have done to date - as you state - suggest some but only a slow vertical flow of water through the bed is recommended for the plenum to maximize its anoxic layer. However no where seems to suggest what is too fast or too slow.
<Well, as you would probably agree-the faster and more efficiently that nutrients are turned into energy, the better your water quality will be. So, it's important to create a system to foster these processes. I do see the logic in your method...very interesting!>
Even with my proposed setup I will not know what vertical linear flow rates I will be achieving anyway. My intent was to concentrate the heating cable into three longitudinal strips so that there will be cold:hot:cold:hot:cold:hot:cold strips the length of the tank (hope this is reasonable explanation). I will be using 110VAC roof de-icing cable. (I have ground fault trip electric and will be very cautious). The cable is waterproof and fully plastic coated therefore should be okay for continuous immersion.
<I have no experience with this device...do proceed with caution if not using an aquarium-specific heater cable system.>
Initially I intend on leaving the cable on 24 hours but could put this on a timer if the mass transfer does not seem to show that the plenum is doing its stuff of removing nitrate. However I will wait 12 months to be sure everything has had a chance to mature and monitor concentrations along the way.
<Sometimes standing back and letting nature do its job really is the best procedure.>
I must admit that I was torn between setting up a refugium in place of the plenum and instead using plants and light. Do you think maybe I should do half and half and plant Caulerpa with a plant spectrum 24W florescent tube on one half?
<I am very anti-Caulerpa for a variety of reasons - I'd use different macroalgae for this purpose...but do utilize some macroalgae. Perhaps you may want to employ a DSB in your main system, and add the refugium in line? Just a thought.>
However - if I do, then I will not know if the main idea ever worked.
<Ahh- the joys of experimentation!>
Lastly, my skimmer is a CPR BAKPak, which is a small footprint venturi in-sump skimmer but only rated to 50 gallons. I have not had a chance to read through all the skimmer stuff you and others have posted. However I do need to finish and get this plenum up first.
<Well, a skimmer is so vital to your system that you may want to push the skimmer up to number one on your list. The BakPak is a great skimmer - but I think it's operating at the edge of it's range in this system, so an upgrade is highly advisable.>
Lastly, I did not add in the previous email that before the plenum I will be putting in a 30 gallon trash can with flow distributor filled with polystyrene peanuts to act as a trickle filter to also increase my ammonium denitrification. The water will drain through the trash can trickle filter by gravity into the plenum. Currently my ammonium is 0.2-0.3. I figure for minimal expense I could get more aerobic degradation. I built this piece ahead of deciding on the plenum, which will presumably also achieve the same end effect of further NH3 & NO3 oxidation in addition to the anoxic denitrification. I have read elsewhere that this is not recommended as enhancing the NH3 oxidation will increase my NO3 problem.
<That's my thinking.>
This seems logical but at worst case if all the NH3 is shifted over to NO3 - I am only looking at a small increase in NO3 to my current concentration. Thanks for your comments and any further thoughts are appreciated.
<Well, you certainly have some great ideas and a nice approach! I think that simple, biological-based systems are always best. You will be surprised at how a simple idea, such as a deep sand bed (with or without a plenum), a great skimmer, good husbandry, and live rock can do the trick. Check out Anthony Calfo's Book of Coral Propagation for some more information on the concepts that you touched on. Also, You may want to pick up Live Sand Secrets by Bob Goemans for a simple review of plenum dynamics. Most of all - Have fun! Good luck! Regards, Scott >
Hi Geoff,
Thanks for a very interesting letter! Let me begin by saying that Sam Gamble can provide you with the 'scientific' literature requested. Contact him at keysmariculture@aol.com.
As for the heating cable, it's an issue Sam and I discussed many years ago when a reader questioned its usefulness. As Sam then noted, and which is discussed in our CD book 'The New Wave,' the more productive temperature range of the microbes existing in the sandbed is in the 70º F range. Keep in mind the microbes themselves exist on the sand particles in the bed, they do not exist in the plenum area (void space). With that said, two problems arise from heater cables located in the sandbed. The first is that the area nearest to the cable will be the hottest, thereby effecting the well being of any microbes/microbial processes nearby. Also, the quality of the cable itself comes into play, as some are not too well regulated and/or do not dispense heat evenly. However, even more important is the fact that the generated heat rises, and causes rising convection currents that work against the downward flowing diffusion process. It's those downward processes in a plenum bed that are invaluable when it comes to microbial processes being in a 'balanced' state. Again, if you would like more in depth reasoning, contact Sam for the related 'science speak' side of the issue.
When it comes to the oxygen content of the plenum, there's been much conjecture about its presence, lack of presence, or how it would get there. As mentioned in the FAMA article, be assured it does accumulate in the plenum at a greater amount then present in the bed above (Sam has personally tested it.). And that's the reason plenum systems are so much more efficient than sandbeds directly on the aquarium bottom. It's that small amount of oxygen that keeps the majority of the above sand zone in an anoxic state/condition (0.5 - 2.0 mg/l). Something that deep beds directly on the aquarium bottom "do not' accomplish.
As for oxygen taking a direct path to the plenum through an opening of some kind, that is not as logical as it sounds. If that were to occur there could well be an access of oxygen in the plenum as it would then tend to be in balance with the oxygen in the bulk water. That would then halt denitrification in the above bed and result in a system with high levels of nitrate because only nitrification was mostly occurring! And, because the levels of nitrate and other compounds in the plenum space vary, it appears the plenum is a moderator/reservoir where bulk water excesses are temporary stored until the bacteria in the very efficient anoxic zones can fully process them. Keep in mind there are often temporary or ongoing excesses in our aquariums and ever increasing levels of nitrate should cause every aquarist to realize that his or her microbial processes are not in balance. If they were, then bulk water nitrate levels would be extremely low.
And I must add that I truly believe efficient utilization of nutrients by bacteria is much more important than that of export. When one concentrates of microbial balance, less time, cost, and effort need be put into export!
There are some areas in your letter that I would like to add some additional comments. I agree with Scott that you need to 'greatly' reduce the phosphate level, and that most phosphate comes from the food fed and the water supply. His suggestions for correcting should be heeded. Yet, when it comes to the phosphate level, I would prefer something closer to 0.015 mg/l and have found that when that level is attained, there is very little or no further algae growth. To accomplish that in a previous aquarium I first needed a test kit that would accurately attain that level. I used the Merck phosphate test kit 1.14445.0001 to accomplish that goal. And I've found that 'iron' based phosphate removing media is far superior to the aluminum-based products. Also, I should add that I never found water changes to be an effective way to control high levels of nitrate. Once the change is accomplished, nitrate from deep inside rock or the sandbed will flow back out into the bulk water and the level in the bulk water will quickly be what it was a day or two before the change was made. Yet, water changes are beneficial for most systems for many other reasons, as is quality skimming, and the use of the Poly-Filter.
Will you ever get the nitrate level low, and low would be >10 mg/l, is a good question. Increasing the area for nitrification with additional trickle areas will probably do away with any on-going nitrite, yet increase the nitrate level. If it were my system, I would think about creating a very large plenum area and/or possibly reducing the existing bioload. Mother Nature can only do so much! And, keep in mind, there is some denitrification equipment on the market that might be helpful if reducing the bioload is not amiable.
Hope this helps,
Bob
Hi Bob,
Thanks for responding to my e-mail. I did have some additional questions regarding plenums that I hope you can answer. I would like to set up an Auxiliary plenum using a 55 gallon tank (the main tank will be 75 gallon). I know the recommendations are to typically run about 25 - 30 gallons/hr through the auxiliary. If this is the recommended flow rate, do you suggest continuing to use a sump and pumping water through the auxiliary using power heads? If I was to place the plenum in the main tank, and follow the recommended water turnover rate of 4-6 times/hr, why is there such a dramatic difference in rates between the main tank/auxilary plenum?
In your book, Live Sand Secrets, you recommend using a few small pieces of live rock in the auxiliary system. Should there be any special consideration for lighting? Also, should I use live sand in the main tank and if so, how much? Finally, with regard to activated carbon, I have used chemipure/polyfilters when keeping fish only systems. Have you ever used these products and do you have any other recommendations? Thanks again for your time. I like your web site!
Jason Isely
Hi Jason,
As for water flow through the auxiliary plenum, that is usually a smaller system than the main show tank. It does not contain any corals or fish, and slower water flow simply allows for more 'dwell time.' In the main system, the dwell time is automatically there since the water is not going to another tank for biological filtration. And flow rates in the show tank have little to do with what's occurring in the sandbed. The flow rates in the show tank are higher for the benefit of the animals, not the bacteria.
If the auxiliary plenum system is used solely for filtration purpose, no lighting is required. I turned my auxiliary plenum into a sponge tank. If you want to use it as an oppositely lit refugium with some small creatures and as a slight pH and alkalinity boost for the main system, use common household fluorescent lamps.
As for ChemiPure/PolyFilters, have used both and they are excellent products and would continue their use in your marine system. Hope this helps,
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 the 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, some very knowledgeable folks are now rethinking that wisdom!
The Oceanographic Museum of Monaco has a full-sized coral reef system called the "Lagoon of Sharks.' 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 in England set up their filtration system with a very large plenum. In fact, it's 16 feet long and five feet wide and you can see a photo of it on my website (www.saltcorner.com). 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! Prior to that, about three years ago, I did the same with a local shop. Their system nitrate level was almost always 2 ppm or less.
But it should be kept in mind these plenum systems are dedicated systems with wide-open sandbed surfaces, and they work well! Yet, in individual hobbyist tanks containing a heavy fish-only load, I would still consider using trickle filters and/or fluid bed filters, which are easier to service than a sandbed. Besides, fairly high nitrate levels won't affect most of these fish. 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 too much system tweaking. Hope this helps,
Bob
Hi Bob,
I've written you before, and have since read all your books. My current question regards a plenum that I have set up in a Discus aquarium. I have set up the plenum in accordance with the instructions regarding construction, substrate size and depth. However, I substituted river sand of the same size for obvious reasons. I cycled the aquarium with a Freshwater bacteria culture product approximately four weeks ago. Today I ran a battery of tests, and was surprised to see non-detectable nitrate levels. I was using a multitest nitrite/nitrate test kit, and also ran a reference test with same results and a second nitrate test with same result. Would you happen to know whether the culture product could have contributed to a bacterial colony in the substrate so quickly? The sand was quite inert before I cycled the aquarium. Needless to say, I am a firm believer in NNR and read your column in FAMA every month. Your help and your contribution to FAMA are greatly appreciated.
Russ Schultz
Hi Russ,
One month would be a little quick to cycle the aquarium fully, no matter what brand product was used. If your system has a reasonable current bioload, i.e., fishes and feeding as necessary, and there is no sign of ammonia or nitrite, then I would feel comfortable in saying the system has probably cycled. Yet, without knowing the present bioload I recommend caution and further testing.
Bob
Hi Bob,
My understanding is that cyanobacteria can fix nitrogen. I have had slime algae problems in the past in my well-lit freshwater plant tanks when nitrates were low, yet phosphates were high. Therefore my thinking in freshwater terms is to either dose nitrates or use water changes to reduce phosphates. In mature freshwater tanks, cyanobacteria appears when nitrates are severely limited with all but a trace phosphate.
Does marine hair algae only need phosphate? And if so can I assume it can utilize calcium phosphate bound to live rock? If this is so, then hair algae will have a bloom cycle and be gone if all new phosphate is limited and the precipitated phosphate bound rock is exhausted.
Am I correct in this thinking. Will any sort of phosphate sponge help when phosphate is bound? I anticipate the precipitated phosphate to be poorly soluble. If so which brand name is preferable.
Thanks Again,
Drew Young
Hi Drew,
Extremely good questions, however, a few misconceptions.
Cyanobacteria/slime algae begins as a 'biofilm' which is nothing more than a very thin film or grouping of microorganisms that have found a home in a suitable neighborhood. Neighborhood preferences are where the current is somewhat slow, an adequate food supply exists, and where there is a preferred light spectrum. It can form on any solid matter that remains in contact with water, even living tissue.
The required nutrients are phosphate, nitrogen (as nitrate, nitrite, and/or ammonium). When the neighborhood is right, these films grow larger and/or hair algae spores find comfortable places to put down a mat-like growth and begin their plant-like structure (hair algae).
Since 'nitrogen' is probably the primary nutrient for getting these pest growths started, closed systems are the perfect place! Nitrogen is almost always above that found in the wild. Phosphate is also above that found in the wild, and the more foods that enter the water, the more phosphate, as foodstuff and possibly the tap water used for evaporation makeup and water changes are the two main sources of the compound in our aquaria.
Nitrogen (basic foodstuff) is normally high near the substrate-bulk water interface where mineralization and nitrification is occurring (yet maybe not too high in the bulk water). Equipment such as trickle filters and fluid bed filters discharge nitrate into the bulk water, not helping the situation. If small adjacent supplies of phosphate (energy) are also available, it's almost the perfect place to call home. Since these are autotrophs, add to this environment a poor quality spectrum (red wavelength) and somewhat poor water movement,, and the neighborhood becomes the best possible place to call home!
Once started these existing forms of cyanobacteria (slime and hair algae) would be unaffected by additional nitrogen additions to the bulk water, except to possibly create new areas of growth. Nor would water changes provide any long-term solution to a nitrate problem. Water changes are a nothing more than a very temporary treatment as any nitrate inside the bed or rock will simply flow back out into the bulk water within a day or two and you're back to square one. It's necessary to get to the roof cause. That would be doing what is necessary to reduce/rid the cause of any nitrogen and phosphate levels in the bulk water, and physically remove unwanted growths. And to continue to remove these growths as often as necessary while improving the quality of the bulk water and accomplishing sensible sandbed maintenance.
As for calcium precipitated phosphate, such as precipitated with Kalkwasser, it does not generally reenter the bulk water. Generally is the key word! That's because in the bulk water area the compound is quite stable since it can very easily maintain its electrical 'charge' balance. In other words, the phosphate compound is four oxygen atoms and one phosphorus atom (PO4) all held very firmly together by their electrical charges. If the calcium phosphate compound were to somehow be transported into an anaerobic area, bacteria would attack the compound for its oxygen elements, thereby releasing the phosphorus element. Phosphorus by itself is not an algae nutrient in the sense as is phosphate/nitrogen (ammonium, nitrite, and nitrate). Yes, 'phosphorus' is necessary for the microbes to carry out their metabolism processes, but its not a direct player as an algae nutrient. However, phosphate, a byproduct of that metabolism, is!
However, there's another 'possibility' when it comes to cyanobacteria. Once cyanobacteria mats/biofilms/hair algae begin, the area under the mat is subjected to reduced oxygen levels. If the calcium phosphate compound is under the mat area, the bound phosphate could be liberated due to the bacteria seeking the oxygen elements. To what degree has not been determined to my knowledge, nor exactly its value to the structure of the mass. However, it certainly must help in the initial growth stage. And, it should be understood that the continued growth of the mat or hair-like cyanobacteria becomes independent of nutrients in the bulk water because its mostly fed by what's being produced in and just under its mat area. In fact, at this stage, the reduction of light is ineffective. And, as a last comment, phosphate, as orthophosphate might be released to the bulk water by tunneling infauna while its being oxidized, but even that is fairly rare in closed systems.
In freshwater aquariums its possible to use a small amount of brown sugar or unprocessed honey monthly to feed the aerobic cultures that use the ammonia as fuel, thereby mostly doing away with nuisance algae. As for how much, one teaspoon in a 100 gallon aquarium would suffice. Table sugar does not have the same carbohydrate value because of bleaching, as do these unprocessed sugars.
As for the use of a phosphate sponge, I do not agree with those that say its possible to absorb the phosphate already bound to calcium. That phosphate would/could only be released by acidic conditions or reduction by microbial processes. However, 'iron' based products are extremely useful in removing it from bulk water. There are three pad brands that I know of, and a growing number of excellent iron-based powdery products. (For those reading this, contact me for brand names and recommendations) Unless green is your favorite color, one of these iron-based products should be used from startup.
There has also been some controversy over the safety of aluminum-based phosphate removing products where some soft corals are concerned, i.e., Sarcophyton sp. I have been recently informed that at only a pH of 8.5 and above does aluminum-based products possibly become harmful to these type soft corals. I would like to see more data about this possibility and if anyone reading this has further data, please contact me.
Hope this answer's your questions.
Bob
Dear Bob,
I enjoyed your website. I guess that the biggest problem is that there will always be a huge debate over the dsb and plenum methods. Since I've been in the hobby, I've set up several tanks for myself. 3 were plenum equipped, 2 with dsb's and 1 ecosystem. 2 plenum tanks were extremely successful. So successful that the reason for the 3rd one was that the other 2 couldn't handle all of the grow out. But unfortunately, the third one wasn't so successful. As a matter of fact, it within weeks, all corals began to die. I only managed to save several zooanthid colonies, a green moon coral, and some xenia. I decided to transform this system into an ecosystem mud style filter with lighting over the caulerpa 24/7 and no skimming. That method polished off the last of my hardiest corals and caused drastic increases in a once minor aptasia problem. Deep sand beds were attempted in other aquariums, one being my mothers seahorse tank. Algae in these dsb tanks were so bad that I had to physically remove the rocks and scrub them.
I have since removed the dsb form the seahorse tank and daisy chained a plenum equipped tank underneath. After about a month, we no longer remove the rocks from the tank to scrub clean. There are very few janitors in the tank... less than one per gallon and at most, we have to use a mag-float once a week to clean a slight film that grows on the glass. I do not know why I am being so stubborn about adding this dsb into my main display while having an equal sized aquarium housing a plenum. I guess I am just getting too wrapped up into the debate and can't help but feeling that maybe I did something wrong with the dsb aquariums, even though I've waited the same amount of time that I did with the plenum before adding any livestock. I know what I did wrong when I set up my 3rd plenum that failed... I set up a 90 gallon using the existing sand from my other 2 aquariums along with some new "dead" sand that had to be added to make 4 inches, and added in all of the livestock form the other 2 aquariums to the 90 in one day. I never gave that system a chance. And due to time restrictions ( a poor excuse at the truest sense of the word) I wasn't doing my minor amounts of required maintenance. I'm not going to say that I think the dsb method is wrong. I'm sure there is more or less that I could have done to make it more successful. Reguardless, I will go with a very shallow 2-4mm thick sand bed on the bottom of the main display. 1/4 to 1/2" thick
As for the comments by Dr. ron... or whatever they call him, His insults of you truly were unprofessional. If you were to ask me, I'd say that he is just trying to take your audience away. He chose to attack someone personally rather than focus on why his method is better. Right or wrong as per his method being better than someone else's, he showed bad business and poor tact in his direct criticism. I wouldn't even bother acknowledging him on your site.
Chris
Hi Chris,
Thank you for your honesty and a well-written letter! Unfortunately there are people in this hobby that would rather attack new thinking as they find it a way to keep their name in front of the masses or benefit their business. Honestly, an aquarist can have a great system using any method, i.e., undergravel filter, DSB, plenum, Berlin method, shallow bed system, and/or bare bottom tank! The most important thing is understanding the capability and limitations of the method used in relation to the bioload desired. Once those two aspects are in tune, any type method will result in a great system!
As for the plenum method, my only goal there is to have aquarists understand its capabilities. What they do with it after that does not put money in my pocket. But if they do understand its capabilities it does make me feel like I've accomplished something to benefit my hobby and our wet pets!
Cheers,
Bob
First Letter
Dear Dr. Goemans,
I have read your work in Freshwater Aquariums and Marine Aquariums (FAMA) and Practical Fishkeeping (PFK) magazines, and especially enjoyed your article about your solar powered aquarium a while back. Back then, I read that you preferred a shallow sandbed of about 2 inches (5 cm) rather than a deep one for the main system, with your plenum system in a smaller tank below the main system.
Since then, I have decided to go with a Berlin system with a sandbed of 2 - 3 inches (5 - 7 cm) using aragonite sand (2 - 3mm). The tank is 4 x 8 foot and 2.5 feet deep. The system included an Aqua Medic skimmer, Kollarin calcium reactor, Aqua Medic nitrate reactor, and a Deltec fluidized reactor filled with ROWAphos. The system is topped with RO/DI water. I also change 10% water per month and run carbon occasionally, and always use a Poly-Filter. There are four pumps providing a 4000 gallon turnover, which comes from the two sumps beneath my 550 gallon show tank. Lighting includes two 400W 20K Radium metal halides and six 250W 6500K metal halide lamps.
The tank has been running with live rocks taken fresh off the sea floor not far from my house. These rocks are covered with red and pink algae and a host of microorganisms. There are some small gobies, shrimps and crabs that came with the rock. I also have a 6 inch giant clam, and there are no other fish. I have also purchased some Eco-system mud, but have not decided to try it yet. The tank has been circulating for a few months with the rocks before any introduction of new corals, and all water parameters appear to be fine.
The soft (Nephthea sp.) and hard coral (Seriatopora hystrix?) seemed to be doing well, growing on the live rocks. And many new organisms, especially bluish and yellowish sponges, have appeared and grown since. Hence, I decided to add more corals.
But as soon as more Nephthea sp. was introduced into the tank along with some hard corals (3 different Acropora species and 3 Pachyseris rugosa), something happened. One of the new Nephthea dissolved overnight on the first day of introduction, and by the next day, all the other healthy Nephthea died as well. Worst, two of the Acropora corals appear to be dying also. The green one has been excreting something into the water column and it now appears to have lost its bright greenish color and turned brownish green.
But other corals remained healthy, especially the Seriatopora species. All the rocks and corals have been taken from the same shallow reef about 10 feet deep. There is now an awful smell in the sumps and I know something terrible has gone wrong. However, the skimmer is still skimming normally with no visible additional bioload.
Why have these soft corals died off when these were supposed to be an easy species to keep? Why have some hard corals died while others appear to be doing fine? Meanwhile, the giant clam appeared not to be affected. Some of the new young Nephthea sp. growing on the live rocks appeared to be suffering and some of the newer sponges have reduced in size during the last 48 hours. I have not change the water yet.
Please assist me in determining the cause. Have the corals been fighting one another? They have been given plenty of space since the tank is rather empty. As all the corals and rocks came from the same reef, therefore there should not be any problem with compatibility. Would a Eco-system mud refugium help?
I desperately need your expert opinion on the matter and your prompt reply is deeply appreciated.
Thanks
Herbert Hiew
Answer to Letter 1
Dear Herbert,
Everyone calls me 'Bob.' Let me first say you have excellent equipment! Yet knowing your water quality parameters would also help in resolving some of these problems (ammonia, nitrite, nitrate, pH, etc.). I also wonder where you are located, as being able to gather your own specimens these days is quite rare.
However, the one comment about a brown substance oozing from the stony corals, which is zooxanthellae, is probably happening because of a change in light intensity. When these corals endure a sharp increase in lighting intensity, they discharge some of their zooxanthellae because it's no longer needed to make a good portion of their food supply. If the change in intensity is too severe, it can often kill them. You have very intense lighting and the change from their original location lighting to your tank may be far too severe for them. In the future, start them on the bottom of your tank, and over the coming weeks move them higher. They could also be affected by what's in the paragraph below.
As for the soft coral problem, I've heard of Nephthea doing that when the new specimen experienced a major difference in salinity, and/or light intensity (or another water parameter). Would either be an answer in your case? And, if one would dissolve, it could radically affect water quality as some have toxins that are still not understood and/or what else would/could be affected by these chemicals. And with the sump water smelling (what kind of smell?), it is probably time for a major water change. And sponge reaction is a clear sign of a toxin - but what is a good question. Water change, water change, and water change appears to be the next move.
Cheers,
Bob
Second Letter
Hi Bob
Apology for addressing you as anything other than Bob.
This is my second e-mail to you today. I understand that you have reviewed the new SpectraPure LiterMeter III in the March, FAMA. However, I did not have a copy, as it was sold out at my local bookstore. As I have placed an order for it, including a water exchange module to change my water, I want to know if it's a good idea to change my water slowly using this unit. Would it affect water chemistry?
Also, I have heard about the ECO-Aqualizer but was skeptical until I read your review. I still do not understand the working theory behind the device. But as long as it works, I am willing to give it a try. However, without electricity to power the unit, how long would it last? Is there a resin or bulb to change?
Also, I noticed that the manufacturer has them in three sizes, but none big enough for the tank my size. Could it be installed in series using only one pump?
Please advise.
Herbert Hiew
Third Letter
Hi Mr. Goemans,
Thank you very much for your insight.
First of all, I am living in Brunei Darussalam on the Island of Borneo. I have harvested the specimens about a mile off shore at a depth of 10feet. I only take one or two specimens at a time when I go out to sea. Most of the specimens were taken from the seafloor already detached from the coral formation. Many were broken off either by ship anchors or damaged from heavy current. The temperature on the reef is 28°C.
I went out to the beach directly across the island and took some sample readings after reading your e-mail. pH 8.2, KH 6, SG 1.0215.
The parameters in my tank are: pH 8.1 - 8.3, KH 7 - 8, SG 1.0225, PO4 - 0, Nitrate 2.5 - 5ppm, Calcium 400, Nitrite and Ammonia: 0, Temp: 26 - 27°C
I noticed a difference between the SG between my tank and the sea. Is it considered major? I am also taken back by the KH level in the natural seawater. I have read that it should be kept above KH 7.
Since the last e-mail, I have changed 10 percent of water. The microorganisms seemed to be recovering now. Some sponges did shrink in size after the trouble started, but they have resumed growing since. The rate was surprisingly fast. Is it normal? New small Nephthea brunches growing from the live rocks were affected during the first few days, but they too have recovered.
The greenish hard coral, which was oozing brown substance, have died. However, there was new greenish growth appearing once again from the base and it did not look like algae. What could it be? The same greenish growth could be seen affecting another coral not far from it.
I have a lot of bubbles in the tanks from photosynthesis, mainly from live rocks and the sand. I read that it is good to a certain extend because it meant pH would drop during the night when algae consumed oxygen. Would it actually make an impact on my system? I understand that many hobbyists used Kalkwasser during the night. Since I have a calcium reactor, do I still need Kalkwasser?
I have not added anything since. How long before I could resume adding?
Actually, I have left out something in my earlier e-mail. The original chiller was removed because it was not designed for the tank. Only when my new chiller arrived three days ago did I realized the extend of the problem. The temperature was reading 35°C when the new chiller was installed. Could it be the source of the problem? The highest recorded temperature measured in the sea during dry season was 32°C and the lowest was 24°C during raining season - readings taken from my dive computer.
Would adding the miracle mud help? I understand this has become very popular in America and beginning to be in the U.K.
As I am living in a country without any marine shops, and all of my knowledge has come from elsewhere and constantly read Practical Fishkeeping (PFK) and Freshwater Aquariums & Marine Aquariums (FAMA) to help understand my hobby. I also used Kent Marine salt for water changes with RO/DI water made with SpectraPure equipment. Would it be advisable to use the water from the sea? The water is usually green but clear during the dry season. It does become murky during raining season.
Please advise
Herbert
Answer to Letters 2 & 3
Dear Herbert,
It sounds like the problem is solved! You say the reef temperature where the specimens were taken was 83°F (28°C) and your aquarium was 93°F (35°C) when the specimens were added. From what I gather from your letter, the wild specimens on the actual reef in your area can handle higher temperatures during the dry season, and that would only be possible because they experience a very gradual change in water parameters. Since your chiller had gone down before the new specimens were added, your aquarium temperature was far above the temperature where the new specimens were coming from. The sudden water temperature change simply destroyed them and the chemicals from the disintegrating new specimens affected some of the established animals in your aquarium, which had mostly adjusted to the gradual temperature rise. Its amazing to say the least how resilient some of these invertebrate are, along with their recuperative powers when experiencing "gradual" changes as you can see by the recovering specimens. As for the new greenish growth, I'm not going to venture a guess, but in time the answer will become clear. Let's hope its new coral growth.
I would recommend another two 10% water changes before putting more animals from the reef in the system. And, I would slowly acclimate these new specimens from the wild in a holding/quarantine tank before placing them in the main system. Be sure temperature and other water parameters are fairly equal with the main system before placing them in that system. A little care here goes a long way in the longevity of these animals and those already in the main system. And since your present level of calcium is right in line with what's in the wild, I would not consider using Kalkwasser at this time.
As for your other questions, the specific gravity difference between your tank and the beach water is not enough to be concerned about. And as for KH appearing somewhat low in the seawater, so is its specific gravity. If the specific gravity were higher, the KH would also be higher, and in fact, so would the calcium level. I would venture a guess there is a goody sum of freshwater entering your surroundings, either from land run-off or seepage from below.
And, alkalinity can be measured three ways: milliequivalents per liter (meq/l), German degrees of hardness (dKH), or parts per million (ppm) of calcium carbonate. The most commonly used and more correct measurement is meq/l. It measures, in molar concentrations, how much acid can be neutralized by a given amount of alkalinity. A less usable expression is one that expresses the German KH (degrees of hardness), which is an oxymoron since it has nothing to do with hardness. KH, sometimes referred to as dKH, is only the calcium carbonate and magnesium carbonate in the system, not the "total amount of buffering agents" in the system. In essence, dKH readings are really more guesswork at what a system really contains as a "totally" usable base to neutralize acid. Anyway, the conversion for the three units is 1 meq/1 = 2.8 dKH = 50 ppm calcium carbonate. What range, either in meq/l or dKH is required for good maintenance of alkalinity is open to much interpretation. In my opinion the dKH maintenance range should be between 10 to 12 in most reef aquariums.
As for the bubbles, it will drive pH higher during the day and as long as there's not a radical downward slope during the night, I would not be overly concerned. I would test pH during the late daytime, and again early in the morning. If your pH stays in the 8.1 to 8.3 ranges, I would not be concerned. However, I do suggest testing magnesium and relating it to the present specific gravity to find out if it's correct. Low levels of magnesium can yield wider swings in pH.
As for the Miracle Mud product, I see no reason to use it on your system, however, if having a refugium full of worms and crustaceans and macroalgae is of interest, then go for it. You already have excellent equipment that is designed to help promote a nutrient poor system. Why add more things to care for, and why connect a nutrient rich system to a system that is supposed to be nutrient poor!
Whether to use the local seawater or not is difficult for me to answer. I'm not sure of how human waste is handled in your area, or that of soaps used to bath and wash clothes. This is a growing problem worldwide with many countries taking the least expensive way to go and dumping it into the oceans. Believe me, it will come back to haunt us sooner or later, and in many cases its sooner than we thought possible. Unless you are very sure about the quality of the seawater, I would continue to use a dry salt mix and RO/DI water.
As for the Product Review of the SpectraPure Liter Meter III, it is my understanding that has yet to appear in FAMA as of this date (May/03). But I'm going to attach it as a separate file so you can read it. And to answer your question, the slow exchange of seawater in your aquarium will certainly reduce the shock associated with any single amount done at one time. Also, the slow exchange rate reduces your maintenance time when its time to vacuum or clean the aquarium. Since the water change will be accomplished automatically in 150 small and equal withdraws of aquarium seawater and additions of new seawater per day over a certain period of time (decided upon by the user - days or weeks), its simply one less chore on cleaning day so to speak. So, you can have any percentage of your aquarium water changed every two weeks for example. All you need to do is have a place for the withdrawn water to flow into and keep the seawater replacement container from getting empty. In fact, I set this replacement system up on a client's tank and it worked perfectly.
There's no doubt the controversy surrounding the ECO-Aqualizer has been turbulent to say the least. While speaking in Chicago early this month at the first IMAC Marine Conference I mentioned the sad state of affairs on some websites where some individuals apparently use controversy and sensationalism to keep their names in front of the public. In my opinion, they have closed minds and continue to think "in" the box! Its time for a change and I hope aquarists see that the picture being presented by some of these folks is counter to the wellbeing of our hobby. We need to support new and different ideas, however, continue to question those that present new concepts, yet do it in a professional manner. I should also mention the device needs no source of electrical power, nor are there any components that will ever need replacing. Simply flow water through it at the recommended rates. And I understand the unit is good for at least 20 years! As for your system, I suggest contacting the owner of the company, Carl Denzer at: carldenzer@sbcglobal.net as he will resolve that issue.
I hope this has been helpful and keep me posted.
Cheers,
Bob
Fourth letter
Hi Bob
Thank you very much for your insight. You have opened my mind on many things, which I never considered. Your suggestions have allowed me to analyze where I should be going with my hobby and how I looked at things.
Yes, you were right about the possible contamination to my local seawater. There is no sewage system and so everything goes straight into the sea! Hence, the live rocks closer to land are often covered with a slimy coat of filth and a host of algae (red cottonwool-like and red and black slime algae, etc).
I have installed the LiterMeter III with the water exchange modules and I am truly pleased with it. So far, it has been running perfectly. I am still waiting for the Eco -Aqualizer unit.
I would like to add a Caulerpa refugium to reduce my other efforts for nutrient export. I intend to run a bypass from the overflow into the filter filled with two inches of sand. I understand that the water flowing into the filter should be slow. I plan to have a 200 liter tank. How fast should the flow rate be?
Now, I would like to share my observation of the reefs around my area of interest.
I have been diving the local reefs for the past ten years. I have seen reefs disappearing for good and new reefs appearing. The island where my corals were taken is such a place. Often, its reef is smothered by filth from a nearby river. And soon its corals would be choked to death. But within six months, a new and greater and more prolific reef would replace it. The new reef would be as grand within one and a half years. The old reef is still covered with endless forms of algae (red slime, green, black etc). Its current is strong most of the time, and pollution is quite evident, yet some coral species seem to survive there. Why are these corals still growing in these seemingly polluted waters? Like I said, the KH is only about 6 and SG1.0215. Have these reef inhabitants grown accustomed to the pollution? Hence possibly, better closed-system aquarium subjects?
There is another incident that occurred seven years ago. Brunei Darussalam has never seen a typhoon until that day. Nobody knew what happened until it was too late. When I went to the beautiful reef about ten miles offshore, I was shocked to see total devastation. There was nothing but rubble - nothing! The entire reef had been covered by sand. We divers never returned to the spot because it was so destroyed. Then three years later, somebody went and saw something amazing. I went the following week and saw a totally transformed reef.
It was bigger than before and even more prolific. The reef life was amazing. How could a reef grow back from rubble in less than three years baffled me. Now, seven years later overall, the reef has expanded another 500 meters and is covered with more varieties of corals and fishes. Simply amazing!
I see the world crying foul play and proclaiming that the hobby is destroying the reef. But as a keen observing diver, I have seen reefs come and go endlessly. It's like a cycle. I tend to believe that the sea is greater and more mysterious than people think. Like the forest - a fire is not necessarily a bad thing. Maybe, the sea is ever changing just like the entire planet.
I have since included a sea cucumber into the tank. It has been in there for two weeks now. It consumed sand endlessly moving from one place to another. It did also consume some algae but appears to be staying away from some areas of detritus. Is the sea cucumber getting enough food? I do not have any fish in the tank, just the natural small gobies, shrimps and crabs that came in on the live rocks. Hence, I never feed the inhabitants. I feed the corals with Two Little Fishes Marine Snow and H&S Marine deluxe. I find the two products very similar. Should I vary the food using other products? I cannot obtain live phytoplankton in this country, as nobody would ship it by mail.
Please advise,
Herbert Hiew
Dear Herbert,
Thank you very much for the follow-up letter and the description of the surrounding areas. I've seen similar areas where both animal and human waste are piped to offshore areas and discharged without any treatment. In fact, the last environmental impact study that I accomplished was at an island belonging to a foreign government and it had 100,000 gallons of animal waste on a daily basis going directly into the sea. They 'thought' it was falling into the abyss and disappearing forever! Not true, as this "stuff" was separating into different compounds and stratifying with much of it seeking higher levels in the seawater. It then was pushed by water and wind currents and simply added to the other causes of why coral growth was lacking along a certain portion of the shoreline. About a year later, after a very violent storm rearranged that coastline and destroyed most of the facility discharging the waste, I had the opportunity to revisit the area. I saw new coral growth in the area, which meant that the massive water change to the local area and the halt to the majority of the waste products had a positive impact on the area. Mother Nature is determined to survive, sometimes with or without our help. And as for your area, coral animals are far more resilient then we think! And in the wild, slow environmental changes bring biological changes to the existing animals that encompass those areas. Sometimes it's for the better, sometimes not. However, one thing for sure, life wants to go on no matter what shape it takes or the condition of the existing environment. Yet, if we want the pristine reefs that we see in travel brochures, we have to help Mother Nature in some areas. And, there are people who are dedicating their time and resources to just that and you might be interested in checking out their website at www.atollreef.org as it's a group that I personally plan on helping do just that!
And, its difficult for me to say if there is sufficient pollution in the areas of coral growth encompassing your island to substantially affect them without some serious testing. And if the currents are as strong as you say, I doubt pollution lingers for any length of time. However, in nearby coastal areas, its evident pollution exists with all the existing cyanobacteria growths. It sounds like a beautiful area, yet needing the attention of caring individuals such as yourself. Could be a group of concerned individuals should be formed to evaluate the local environment and bring forth those findings to those that have the power to make needed changes.
As for the Caulerpa refugium, that is a possible way to export some system nutrients. I say some because its known that Caulerpa release a toxin called Caulerpicin that can inhibit coral growth and possibly kill some fishes. However, it and organic leachates from Caulerpa that yellow bulk water can be removed with adequate protein skimming and/or proper use of activated carbon. If you do decide to go the road of a Caulerpa filled refugium, the type of species and the harvesting of it are an important aspect for success with this type system. Racemosa, or what is sometimes called "grapevine" Caulerpa is ideal because it's a fast grower. However, the excess must be thrown away, as herbivores will not eat it. Two slower growing Caulerpa species, mexicana and/or prolifera, are excellent foods for herbivores and the excess can be used as a very healthy food source for herbivorous fishes. As the Caulerpa grows, always harvest the oldest one third every few weeks - of course, that time frame depends upon its growth rate but I think you get the point. As for the flow rate between systems, one turnover of the refugium per hour should suffice. And yes, a shallow bed of about one or two inches of sand will suffice for in refugium.
I should add that from what I'm hearing about the ECO-Aqualizer, protein skimmers work much better after one of these devices is installed. Its my understanding the ECO-Aqualizer breaks up the larger water molecules that contain locked in nutrients and makes their removal from the system via skimming a much more efficient process. So you may want to wait until the ECO-Aqualizer is up and running before you decide on installing the refugium. Could be it won't be necessary, saving yourself a lot of extra work.
As for the cucumber, as long as the body size does not dwindle, I would not be concerned. If it does get smaller, its time to return it to the wild where it can get proper nourishment.
And as for some other foodstuffs for your invertebrates, you probably know that phytoplankton is at the top of the numerical food chain pyramid and is of great importance to many of the invertebrate we strive to maintain in our reef aquariums. You could culture it yourself and the 'how to' is explained on my website.
Again, thanks for your letters, and hope this helps.
Cheers,
Bob
Bob,
It has been a long while since I last communicated with you. I am setting up a new 120 gal. reef ready aquarium to replace my old standard 55. This is a reef tank which I have had up an running for 8 years or so. I set the old one up using advise from you on the NNR. I was re-reading your article from MFM June 1996 about plenum methods which you mentioned two ways i.e. one with a screen (two screens actually) over 1 inch of sand and one with a single screen over the plenum then all sand no second screen.
Since it has been awhile have you found one to be better then the other?
Any other insights you can give me on setting this up, cycling etc. I would appreciate your expertise. It has been a while since I started from scratch.
Thanks for you help.
Wayne A. Leathem
Hi Wayne,
And some people say plenum systems crash after a year - such trash!
Actually, if there will not be any digging animals in the system, not using the separating screen layer is the way to go. It simply allows for great bed depth penetration if deeper vacuuming if ever needed because of an excessive bioload.
I have a new website that you may find helpful. Let me know what you think. In fact, my guru and I are working on a total redo of the animal library that will have close to 1000 color photos with info on each animal! That will hopefully be done by mid June. Also, to be added will be a section on all aquarium equipment, and general system maintenance procedures. The goal is to have the most professional and informative marine site in the world!
Hope this helps and keep me posted,
Bob