Facts, Questions, and Answers

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.

Q&A Second Half 2004

Dear Mr. Goemans,

I live in Portugal and I have been a freshwater hobbyist for the last twenty years, though I have paid more attention to discus fish in the last six.

My intention is now to try a reef tank in my new apartment so I'm already planning it. I'll move in a year time and until there I'm going to read my whole "archive" of FAMA and TFH magazines that I have collected for the last 4 years.

I have already ordered several books through a friend of mine who is now in Miami on holidays, including your "Live Sand Secrets" and "Protein Skimming and Activated Carbon Secrets" booklets that I hope to receive soon.

Meanwhile, I would like to have, if possible, eventual additional information on NNR Plenum method by e-mail.

I would like also to hear your opinion about my intention to complement the plenum system with some kind of filtration using algae (Caulerpa). My idea for now is to put the plenum in a sump as you recently suggested and eventually make the water that comes from the plenum to pass through an algae bed, to help controlling nitrate and phosphate.

Thank you in advance for your attention

Cesar Silverio (Lisbon / Portugal)

P.S. I'm sure the article about Plenum Myths published in an old August issue of FAMA magazine caused you some concern.

Dear Cesar,

As for additional information on plenum type filtration, you're in luck as our interactive CD-ROM book (on a business card sized disc or regular size disc) "The New Wave" that Sam Gamble and I spent six years researching is still available. It leads the reader through the history of the aquarium to the present confusion centering on live rock and sandbed filtration. It factually focuses on the microbial side of filtration issues and presents leading edge data that has been reviewed for accuracy by a biochemist. If you want to understand how deep sandbeds, shallow sandbeds, mud systems, plenum systems and others function, you'll get the information right down to the microbial level! It's written with the beginner in mind, however, it also contains much advanced information so as to satisfy both the sophisticated aquarist and professional aquarium caretaker. See my website for ordering locations if interested.

As for using a combination of algae and a plenum system, one actually works against the other. One strives for a nutrient poor environment and the other requires a nutrient rich environment to exist.

As for that article in FAMA, the magazine received a very large amount of complaints about printing such a poorly written and thought out article. Actually, I met the author, Brightwell, at a MACNA event in Baltimore. He was a salesman for Kent Marine products and was the person who also wrote those negative ads on other company products that appeared in FAMA for quite awhile. In fact, he told me he wrote those ads. FAMA finally stopped those unprofessional ads after I mentioned they were the only magazine in the world allowing such negative ads. Then they suspended my column for a few months because they suddenly received a complaint that I was not giving equal coverage to all company products. Where that complaint came from is anybody's guess. But since then, things have gone well with everyone realizing I present fair and balanced views along with thoughts based on many decades of experience.

Bob

Hello Bob,

Thanks for your quick response to my last email. I wrote regarding nitrate questions and the natural reef denitrification system. I bought the test kit you recommended and it reads zero to a slight trace of nitrate. I'm also now showing trace nitrate-nitrogen readings with some other brand test kits. This is very confusing because when I initially wrote you my nitrate reading was approximately 20 ppm and I 'was' testing nitrate-nitrogen. I now realize I did not explain which brand kit I was using, therefore you thought I might only be testing for the nitrate molecule, not the nitrogen portion of the compound. However, the drop in nitrate came after we experienced a power failure and the tank was without power for about 12 hours. After the power came back on I accomplished a 15% water change and then tested the nitrate. It was extremely low! Does this acute drop in nitrate make sense to you?

Also, I'm now having a battle with algae, and not winning. I reviewed your booklet Marine Algae Control Secrets, and Julian Sprung's Algae Problem Solving Guide. A plethora of great information in both! However, one of my biggest problems is that I'm red/green colorblind so proper identification of some types of algae is very difficult for me. I will send some photos with this email so you can see what I'm talking about. I also have a few other questions:

1. I have been using very small doses of a product that contains potassium permanganate. Even though it may be a waste of money, it makes me feel better to see my ORP rise to over 400 and stay there. Yet, I don't understand how or why this chemical works, therefore decided to stop its use until you can shed some light on this topic.

2. About five months after my reef system began I had purple coralline growing on the back tank wall and all over its small amount of base rock. But I have not seen any new purple coralline growth in the past three months. In fact my once perfect bright purple Fiji rock is now dull and becoming overgrown with what I think is brown diatom and some hair algae. Also there are parts of the rocks turning grayish tan. I will also include some photos of this.

3. There is always a lot of diatom algae collecting on the front and side walls and if I don't clean them every day it becomes a lot of extra work to get them clean. Also in my overflows there is a large amount of long brown algae that looks seaweed-like. I decided to let it grow so it would consume nitrates since it was out of sight. Am I off base here?

4. There are three 175W MH 6500K lamps, and four 72" T12 VHO lamps (two super actinic, one actinic white, and one wide-spectrum lamp). The super actinic lamps are on for 14 hours per day, the other two VHO lamps are on for 12 hours per day, and the MH lamps are on for 10 hours per day. These bulbs are all eight months old. Do you think the age of these lamps has something to do with my problems regarding the coralline growth? I was planning to replace them in about 4 - 5 months. Does this sound correct?

5. I have a 200 gallon eight foot long tank with 4 outflows (two on each side, and two in the middle), running approx. 2000 - 2200 gallons per hour total current with an Iwaki MD 70 RLT and Custom Sea Life T-3 water pump. I siphon detritus weekly and pluck as much hair algae as possible every couple of weeks. I also siphon and mix the sand bed. At this time I'm not utilizing any powerheads or wave makers. How important are wave makers and would it behoove me to use them/one, and where should I place them?

6. For a cleanup crew, I have about 125 red/blue hermit crabs, 2 horseshoe crabs, 1 large Sally Lightfoot crab, 2 - 3 Emerald crabs, 2 Banded Coral Shrimp, 1 Scarlet Cleaner Shrimp, 6 Peppermint Shrimp (that I haven't seen in about 4 months), 3 brittle stars and about 75 assorted snails. In a past issue of FAMA you mentioned the common sea hare, and the Lettuce Slug as possible helpers. Do you think they would help me as well? If so, how many would I need, and where could I find them? Are there any downsides to utilizing these animals, besides cleaning up after them?

7. Would I benefit from placing macroalgae in the tank?

Also, there is approximately 250 pounds of live rock, with 75 pounds of base rock piled single filed so about 65% of the sandbed is exposed (sandbed is about 2" deep). Water make up is done with an R.O., which I'm about to add a deionization canister. I do a 15% water change every 4 - 6 weeks via tap water filter (deionization cartridge). I am presently looking for the phosphate reducing pads you mentioned in a previous Sand-Mail column. Have also been using a cheaply made protein skimmer, but after reading your reviews of several brands, have decided to acquire a much better brand, one which has a John Guest fitting for my calcium reactor.

The only thing that I add to water is iodine, and I feed brine shrimp and red or brown seaweed daily. My present water values are as follows: pH 7.9 - 8.1, ORP 380mV, Temp. 76 - 78F, SG 1.025, Ca 420 ppm, dKH 24, Alk. 8.5 meq/l, Nitrate 2.5 ppm, and Phosphate 0.1 ppm. And I only have seven fish, 2 Maroon Clowns, 2 Green Chromis, 1 Coral Beauty, 1 Sixline Wrasse, and 1 large Yellow Tang.

My immediate plan is to try and decrease my PO4 levels and utilize a more efficient protein skimmer, but I am very concerned about the condition of my live rock, and the lack of new purple coralline algae growth. Wondering if the damage done is reversible, and don't have the first clue as to how fix it, if possible. Hope this is enough info for you. Thank you in advance for you response as your advice means a lot to me.

Thanks again.

Brian Tapasto (Charlotte, NC)

Hi Brian,

Thanks for your feedback and further information/questions, of which I wish I had all the right answers! Let's first address the nitrate situation. If you had an undergravel filter and lost power, the nitrate drop would make 'some' sense. In fact, that's why Sam Gamble got involved many years ago when the plenum method was still a mystery. The systems having an UGF in the public aquarium where he was the head aquarist actually did better than those where the sandbed was directly on the aquarium bottom during a five day power outage, and they also had a significant drop in their nitrate levels! Anyway, the loss of oxygenated water in your system may have created more zones for denitrification. A water change would have contributed somewhat to that reduction. Or you may have incorrectly read the tests kits the first time. But the good part is that a nitrate problem no longer seems to exist.

As for the potassium permanganate product, it burns up/oxidizes the organic matter in the water, which is what lowers the redox, therefore making the water more clean/clear and thereby raising the redox/oxygen content in the water. Not something I would recommend be used on a continuous basis, however, it can occasionally be used to improve water quality in aquariums where overall system organic content is too high. That's a nice way to say system husbandry is no longer what it should be! And it's a product that should never be used if the system is not equipped with an ORP meter, and keep in mind, anything over 400 is chancy!

Coralline algae or the lack of it is often a question. Usually I find the problem in the area of improper maintenance of alkalinity, salinity, and/or magnesium. In your case, alkalinity appear far too high and would suggest reducing it to about 3.5 - 4.0 meq/l, and also testing for the magnesium level, which must be related to salinity before being adjusted. When you have the magnesium level, let me know the aquarium's salinity and we will go from there.

As for brown diatom on the side panels, there are a couple of reasons for this nuisance. One, your tap water is probably high in silica, and I know of only one brand RO/DI unit at this time that will fully resolve that situation, and its described in the Product Review section on my website. Once you read that review, you'll understand fully why I recommend and personally use this brand unit. Once the water coming into the aquarium is fully processed, a second source of silica/silicate is from a very active nitrification process where some silica-like byproducts are produced. Stirring the sand too often only causes the bacteria to have to reestablish itself. Ever notice how the sand surface turns a little brown after vacuuming it! You may want to reduce the vacuuming to once a month, and give some thought to your brand RO equipment. Or at least contact the company in my review and ask them if they have some add-on equipment that could resolve the silica/type of silica that is presently slipping through your present equipment.

As for the stringy brown algae in the overflows, I'm not sure what that is. But, whatever it is, that area needs more frequent cleaning. I would not simply allow it to go on without cleaning it out. Possibly, it's only a diatom that has compounded itself because it has not been removed and the silica/silicate and light spectrum continues to be there for its growth. You might want to take a little bit and look at it under a microscope. Hopefully, the algae cell does not have a tail, therefore a diatom. But if it has a tail, its then a dinoflagellate and other steps need be taken, besides a good cleaning.

I see no need to change your lamps at this time, as the MH lamps should be good for about 16 months. The VHO lamps, if they have end caps/or their ends are not too dark, should at least last for about 12 months. And that's total life span, not an additional number of months. Also, I recommend upgrading to 10K instead of 6500K when the time comes. Your eye will like the change! Without knowing the type corals are in the aquarium, I can't judge the photoperiod, however, for most soft corals and some medium light loving stony corals, your photoperiod appears to be okay.

You have quality pumps and the total flow appears to be good, and with four outflows, I would surmise the system's circulation is at least fairly good. Yet, if anything, the flows are always the same direction and because of that, some dead spots in the tank will probably develop. That's where a quality wavemaker comes in handy! By causing on again and off again currents that interact with existing steady flows from your outflows, different circulation patterns will develop. This greatly benefits everything in the aquarium. Where to place powerheads hooked to a wave-making device will take some experimentation on your part. First, they should be where they can always be easily serviced, yet not too conspicuous. And of course where they do what you need them to do.

When it comes to sea hares, they are gluttonous algae consumers, and if you're willing to try one, it would probably have to be special ordered as they rarely show up in the trade. Those who have tried them tell me they are capable of quickly wiping out undesirable growths of algae, in fact, any kind of green algae! However, once under control the animal needs to be moved to another area where there is sufficient growth to support its needs. Lettuce Slugs are probably ok for smaller systems where their movement can be monitored, but in your large system you would need too many. One sea hare would equal a hundred lettuce slugs! And as for placing macroalgae in the tank, I would first get the new skimmer going and correct alkalinity, and if possible try a sea hare before adding macroalgae. You might also want to try applying a small amount of ozone to the new skimmer, as that will help maintain a more stable system ORP than using the liquid product mentioned.

Would also concentrate on lowering the phosphate level, as 0.1 is far too high. A reading of 0.015 or below should be the goal. And either the pads mentioned or one of the several powdered ferric hydroxide, i.e., iron-based products is the way to go. These pads should be available in the better local shops, or via mail order. If you go with the powdered form, its best used in a canister filter. If you need more information about which products and exactly how to use it, contact me. And I recommend including mysis shrimp in your animal's diet.

Let me add, there's an 'Algae page' on my website that contains photos of about 150 species of algae (good and bad) plus 60 known biological control species (fish and inverts) with the control species cross-referenced to the unwanted species of algae. And my new "revised" Marine Algae Control booklet mentions many new species of algae, and their photos can be seen on my website.

Hope this helps.

Bob

Dear Bob,

I don't have the time to go into a long dissertation other than I agree with your general thinking. I am new at reef keeping so I cannot profess to have the background and years of knowledge accumulated by many in the hobby. But I do have an extensive background in the real world of waste treatment that I think makes up for some of my newness to the hobby.

I have just set up a new small reef tank. It is only about 3 months old and as any new hobbyist I am learning as I go. From the start, I felt the only logical approach to any sand bed system was to have a plenum underneath it if you had any hope of it not going bad and causing a major upset in coming months or in a few years. In fact, I have taken it a step further in my system and have set it up as a low rate reverse flow to keep my 4 to 6 " bed always partially aerobic and the bacteria fed. I used crushed coral, 1 - 1.7 mm, as the media and make partial water changes using a reverse flow through the plenum to clear it out every couple of weeks.

Even with this set up, there will always be some anaerobic areas within the bed, however nitrification will still take place. I totally disagree with some people who say use very fine sand because there's more surface area for the bacteria to adhere to. Large surface area's do little good, and can cause a lot of potential harm if the bacteria cannot be fed...in my humble newbie opinion. The question someone should ask these people is, "do they think nitrification takes place on live rock?" Which everyone now acknowledges does take place based on zero nitrites being possible if the tank only contained live rock, no sand bed. If that is the case, why don't they believe that some oxygen in a deep bed is a good thing the way it is in a plenum bed? You still have nitrification taking place. We are talking about a microbe world where a few grains of sand measure like city blocks and will have the same biological diversity in both anaerobic and aerobic conditions, yet in close proximity. Just like on and in live rock.

My background, like yours is from the real world of solutions and effort. I'll let you know how my reverse flow deep sand bed with a plenum works out. Right now it is maintaining very high quality water even with periodic heavy feeding loads to the fish in the tank. The heaviest overfeed is rapidly absorbed and corrected with my set up. I picture 4" of substrate crushed coral cover with happy bacteria just waiting to be fed every time I feed the fish. I am not implying this is the ultimate answer, only that it is better than a large mostly dead sand bed with out flow waiting to go so sour it kills everything in the tank.

John

(I decided to withhold this person's full name and company name)

Hi John,

Thanks for your email and I understand your thought process, however, by increasing the oxygen content in a major portion of the bed by forcing oxygen laden water upward through the bed, you're reducing the physical size of the plenum's sandbed anoxic zone. The only difference between your method and that of a reverse flow undergravel filter is the speed of the supplied water and the size of the sand grains.

As most hobbyists realize, the reverse flow UGF method sends aquarium water to the bottom of the bed, forcing it upward through the bed. This method somewhat increases the areas for nitrification, as oxygen laden water is now also available at the bottom grains in the bed. I say 'also' because its normally available at the bed/bulk water interface. In the standard UGF method, the water is withdrawn from the bottom of the bed, thereby drawing water downward through the bed. Therefore the nitrification process is generally more efficient in the upper reaches of the bed where oxygen-laden water is first pulled downward.

Before I go much further, the key to plenum efficiency is the somewhat small amount of oxygen that remains throughout much of its bed and 'the' actual amount of oxygen contained in the plenum space. After years of study, it became extremely evident that to interpret plenum mechanics it was first necessary to understand the different classes of bacteria existing in general sandbeds and that of plenums, and their environmental requirements/paths. And that's where the science of waste treatment plants and aquariums differ!

In waste treatment plants its important to reduce organic compounds (human waste) to inorganic compounds such as nitrite/nitrate. Therefore the stream of waste is stirred and aerobic heterotrophs reduce that matter to inorganic compounds. Not much different than what happens in aquariums with fish waste/detritus/dead animals. The resultant human waste stream is then further aerated in 'ponds' to reduce the ammonia laden products to nitrite and nitrate by encouraging growths of aerobic autotrophs. The result is sometimes used as a crop/golf course grass fertilizer. Of course, we aquarists want to minimize the "fertilizer" aspect of this process.

As you probably know, there are three classes of bacteria that should interest all hobbyists, i.e., aerobic heterotrophs that reduce organic matter to inorganic compounds; aerobic autotrophs that take that inorganic matter, such as ammonia and perform the nitrification process, and the anaerobic heterotrophs that perform denitrification. Unfortunately the anaerobic denitrification process has long been misunderstood and often misstated. In the course of our research, we (Sam Gamble and myself) found that the so-called anaerobic area/zone really consisted of 'two' different zones/paths each having they own class of bacteria and each accomplishing a different form of denitrification! We decided on using the word 'anoxic' to describe one area/zone and stay with the generally understood word 'anaerobic' to describe the other.

Research showed that dissimilatory denitrification occurred in zones having a small amount of oxygen, (0.5 to 2.0 ppm per Sam Gamble) which we called the 'anoxic' zone. It's accomplished by facultative anaerobic heterotrophs and they fully oxidize nitrate back to nitrogen gas.

In the other area/zone/path, assimilatory denitrification occurred in anaerobic areas (no oxygen/less than anoxic as we defined it), where nitrate is reduced ONLY to ammonium, no further and that's accomplished by obligate anaerobic heterotrophs.

Of course, in the past the 'anaerobic' area was said to be an area where little or no oxygen occurred. However, we found that definition did not suffice if aquarists were to better understand the natural processes occurring in their aquariums. And as for any reference to 'anaerobic' areas by any writer/author, for that to be of true value to the reader, it must define the two above described areas. Otherwise, the value of the term can be misleading.

With that now clear, the plenum (space) acts like a reservoir and temporarily holds nutrients that are not fully oxidized as they pass through the depths of the bed. And that's understandable as we hobbyists often have nutrient fluxes in our systems when maintenance lags or if the system is overfed. And since bacteria live in relation to the incoming food supply, they can't increase their numbers immediately to handle these peaks. This space also stores a small, variable amount of oxygen, usually about 0.8ppm. (Actual tests by Sam Gamble.) This small amount of oxygen tends to keep most of the sandbed above the plenum grid in an anoxic condition as we define it, thereby reducing nitrate to nitrogen gas.

If a highly oxygenated water source is introduced into the plenum, such as you describe, the bed above becomes a zone where aerobic autotrophs perform nitrification instead of the heterotrophs mentioned performing denitrification of one type or the other. Which is what happens mostly in UGF systems. Yes, depending upon the volume of flow there may be some so-called anaerobic areas remaining, however, I doubt very much the hoped for results will be anywhere near what you envision. One thing for sure, you have disrupted the natural downward dynamics of diffusion, and reduced the overall anoxic zones. Depending upon bioload, the nutrient level of the system will probably slowly increase. When or if that will reach a level that initiates unwanted algae growth or severe water quality problems, is impossible to quantify at this point in time.

You also say that water changes are accomplished by allowing the new water to enter under the plenum and slowly pass upward through the sandbed so as to keep the plenum (space) clean. It should be noted the plenum (space) doesn't normally get dirty or accumulate detritus or debris, unless it was incorrectly constructed. In fact, the plenum in all my past aquariums were spotless, even after five years of use. And as for supplying nutrients to the bacteria, a plenum system does that automatically without any outside help from the hobbyist. As noted above, the plenum contains a slight amount of oxygen. This oxygen appears to give the plenum a slightly lower negative electrical charge than the area above it, thereby sending its nutrients back to the sand above, which has a higher negative charge. Keep in mind that positive flows to negative, and nutrients are mostly positive charged, and that the deeper you go the greater its negative charges, except where plenums are involved! This automatic circulation of nutrients between plenum space and its sandbed is another reason why plenum beds far outperform deep beds directly on the aquarium bottom, as their greatest negative charge is on the bottom of their sandbed. And hopefully, after reading all of this its clear why a highly oxygenated water supply should not be introduced into the plenum area. It's simply counterproductive! But if experimentation is your goal, go for it and keep me posted.

Also, keep in mind that the majority of live rock internal areas, depending upon its porosity, is anaerobic (as I use the term), therefore, it can only reduce nitrate to ammonium, no further. And, since the surface of a sandbed is much like a filter pad, where it does it thing until water can no longer pass through it, why does anybody want to clog the sandbed surface with excessive amounts of rock! And for hobbyists that want a lot of rock in their aquariums, could be nitrate levels may be somewhat lower, but the nitrogen factor, i.e., ammonium, is still a viable factor to be concerned about. Keep in mind it can defuse upward in the bed, as can nitrate and be accessible to algae. I often get mail saying the hobbyist has little nitrate, but lots of unwanted algae! And with ammonium a better algae nutrient than nitrate, one has to question the value of so-called anaerobic areas that some in the hobby keep quoting as the way to reduce nitrate levels so as to reduce the threat of unwanted algae growths!

And you're right on about small grain sand/mud! Yes there's more area for bacteria to colonize, however, they are the wrong type bacteria! However, as to being fed or not, they do exist in numbers/live in relation to the available food source/supply. It's just that the result of their existence, such as possibly hydrogen sulfide and/or methane, are not generally thought of as a possible result associated with these very fine substrates.

Finally, I've personally dealt with many of the largest waste management firms when I was trying to find one that could handle hundreds of millions of tons of hazardous waste. Some were antiquated, and/or had the most ridiculous contact terms I had ever seen and/or their management was questionable in 'many' important categories, as was their capital holdings. Of course, this is not a personal view of your company since I'm not familiar with it. But one thing for sure, you're in what I consider a "thankless" business because people in general take what you accomplish for granted, and one that in some areas needs a major overhaul as our population continues to grow. And if I can help in any way, don't hesitate to contact me.

Hope this helps,

Bob

Dear Dr. Goemans:

I would like to start this email with my sincere thanks for your dedication to making this a better hobby. Your commitment to sharing your knowledge to help hobbyists succeed at keeping marine life means a lot to me, and I'm sure many others. I feel I can trust your advice above all others because you have no obligations to promote specific brands, and I've followed your advice on several occasions with no bad results. It is hard to find a source that I can trust.

I have several questions for you. My first one is concerning a snail called Nassarius. They are a detritivore featured in a Coralife News publication volume 1 number 5. I see this publication at local retailers often. In the article entitled Detritis, Part 2 by Dr. Ron Shimek the Nassarius snail is cited as a good detritivore. One of my local dealers is claiming that not only are they detritus eaters, but they then feed it to your corals. I purchased some because my curiosity was piqued, and they are excellent detritus eaters and pretty cute. I enjoy having them, but I haven't witnessed any behavior indicating that they are feeding my corals. Have you heard of any such behavior?

The second issue I'd like to share with you is using the Aquarium Pharmaceuticals Tap Water Purifier Deionizing unit to mix salt water. In the directions it says that it isn't necessary to buffer the deionized water or adjust the pH because a quality salt mix will set the pH at 8.3. I used Instant Ocean salt mix and let the buckets mix overnight with a powerhead in them (outlet pointing up to break the surface of the water for aeration). The next day the pH tested at 7.4. Have you done any research on this product? I was hoping to eliminate introducing the phosphates & silicates in our local tap water to a new reef aquarium. I've used this unit for a year for my freshwater tank with satisfactory results. Any feedback you have on why the ph was so low would be greatly appreciated.

The next question I have for you is about Venomous Cone Snail identification. I have one picture of the dangerous creature in one of my books, but I'd like to know if you have any suggestions on where to further research this snail. I'm the kind of person that needs pictures, so if you know of some good sources of information with pictures please let me know. I have recently found a strange new snail in a reef tank I maintain that is scaring me. It is about 1/4", has a white shell shaped like the Nassarius snail with a spiraling row of black dots from one end to the other. The antenna is clear with tiny black dots.

My final questions are regarding plenums. In your Live Sand Secrets Booklet you mentioned that you were going to try a Plenum on a discus tank. Have you started that yet? Also, the people who have negative opinions of plenums say that there is a great danger in the possibility of the plenum water being released into the system. You didn't really address this issue in your book; what do you have in response to this?

Thank you very much for your time. I look forward to hearing from you.

Wendy Floyd

Hi Wendy,

Thanks for your email, and Nassarius is in a scavenger class of mollusks and is said to feed on dead or decaying matter. Yet, most whelks are carnivorous. Not being a scientist, such as Ron, I would tend to go with what he say's until there is firm evidence to counter that position. I've not received anything counter, nor have I personally tried them.

As for the small water processing devices that temporary hookup to the faucet, they are fine for certain situations. The main problem is their size and that water first does not flow through an RO system to remove the majority of unwanted elements prior to it encountering their resins. Because of that, their resins quickly become clogged and their filtering capacity thereby quickly diminishes. For small aquariums, especially freshwater or small seawater aquariums, they may at first use be quite effective. However, for larger aquaria or more complex systems, more elaborate RO/DI type equipment must be considered. As for their product water, yes most or all of it free from the carbonates that help buffer our seawater aquariums, which in turn help to further buffer newly mixed seawater. In fact, I use Instant Ocean most of the time and in using processed water, find it mixes most of the time to a pH of 8.3 with good aeration (powerhead with an outside air supply). Hopefully you have checked the kit used on another source, such as the aquarium to be sure of an accurate reading.

As for further research on snails, try getting Encyclopedia of Marine Invertebrates, Edited by Jerry Walls, ISBN 0-87666-495-8, published by TFH.

As for a plenum releasing its contents into the bulk water, nothing could be further from the truth! All the details on sandbeds, whether in aquaria or the wild is fully explained in our CD-ROM book called "The New Wave." However, I won't leave you without the following explanation;

"Another fact to consider is there must not only be proper oxygen gradients, they must be accompanied by the proper sequence of electrical charges for efficient use of energy. That can not occur in deep sandbeds used directly on the aquarium bottom or inside that of live rock! The deeper the sand/rock, the more negative it becomes and the more the nutrients are attracted to lower depths. But the same is not true for the plenum system because one of the main purposes of the plenum is to retain a small amount of oxygen, thereby having a slightly less negative redox than the sand above it. This change in the sequence of the diminishing electrical charge with depth sends oxidized elements back to the bulk water, recycling elements instead of accumulating them as what occurs in the deep sandbed on the aquarium bottom."

If really interested in fully understanding sandbed processes, read our CD book. That and other very interesting things are discussed, all checked for accuracy by a biochemist.

In fact, here's the latest comment received - "I'm into chapter 5 of the book now and very much enjoying the information in there :) I've already used some of the more basic information to correct a couple of plenum-related discussions on one online bulletin board! ;) Will take me a while to get to grips with coupling and decoupling of nutrient cycles although I do begin to see how a plenum sandbed is reliant on a completely different set of energy pathways than a non-plenum sandbed system. It also makes sense to me why Ron Shimek promotes so-called deep sandbeds over plenum systems given his love of benthic invertebrates! Both approaches can work, but the plenum system works quite differently and depends far less on the vagaries of benthic invertebrate population dynamics. I also like the way the plenum pushes equilibrium away from storage and towards export. Deep sand beds without plenums would tend to store more, and therefore are more at risk of 'old-tank' syndrome. And this explains Dr Shimek's recent interest in that very phenomenon. Craig Dolphin"

Hope this helps,

Bob

Dear Bob,

I want to thank you for the very quick reply regarding my problem with low pH in my 110 liter reef tank. To refresh your memory, my permutations are; live rock system, aragonite sand, skimmer, 4 power heads, 2 percula clowns, many soft/hard corals and 4 T5 lights, with the pH 7.8 - 7.9, alkalinity 13 dKH, ammonia 0, nitrite 0, nitrate 20/40 ppm, and phosphate at 0.03 ppm. And my problem was that every time I buffered with a pH powder my alkalinity went sky-high.

Based on the information originally sent, you suggested using bicarbonate of sodium/baking soda and asked for more information. Which I did use for a short time without any success, maybe I did not give it enough time (2 weeks). I therefore went back to pH buffering powder and it went up to 8.0 and raised my alkalinity. However now it is down to 7.7 - 7.8 and I fear my water has so many chemicals in it I will never get it up to 8.2 - 8.3. I have done RO water changes with quality salts, Kent Marine, ranging from 10% - 50% changes every 7- 10 days without any positive result in increasing pH.

As for my calcium level, its also down to 340 ppm, and rather than use liquid calcium like I have, I'm now dosing with Kalkwasser per manufacturers instructions thinking I could resolve both the calcium and pH problem. In upping my calcium to 400 ppm I did hope that my pH would simultaneously go up however, this is not holding true.

I was going to go back to baking soda until I tried a sample of my tank water in a 1 liter container with 1/2 teaspoon of soda and left it for 24 hours. I could not believe the result; it dropped to 7.1. Which leaves me wondering if my tank is so much full of everything but the right thing! Does this information give you any further help with my dilemma? My fear is that if I stop buffering my pH will drop even further and I will loose my corals. If there is any way you can help me with my problem it would be very much appreciated.

Thanks from sunny Scotland,

John Kelly

Hi John,

And from sunny Arizona, thanks for the feedback.

Wow, wish I had all this info the first time. There's a story I tell in one of my booklets, which probably fits your situation to a "Tee." It goes like this:

"Let's use a fairly new system as an example where Kalkwasser and a buffer is being used. Alkalinity is 3.0 meq/l, slightly above the Natural Seawater (NSW) level of 2.1 - 2.5 meq/l. pH is about 8.3 and calcium is about 450 ppm. Even coralline algae are growing extremely well. At this time Kalkwasser and buffer additives are infrequently used.

In such cases a false sense of security overwhelms many reef keepers. Why make water changes if everything seems okay think some. Waste money on salt mixes when everything is so good - not me reply others! Besides, some aquarists hear that water changes aren't needed. When asked to test magnesium some reply - test what? Never heard of it! Isn't testing pH and calcium in reef aquariums sufficient they reply. Then there are those who say - hey, since everything is looking great its time for more pretty fishes.

There are now some unforeseen potholes lurking in the aquarium husbandry path. And they are quite easy to fall into unless the aquarist understands the carbonate buffering system (alkalinity). Increasing bio-load and reduced attention to certain water parameters is now setting the stage for a decline in water quality. To complicate the situation the reef keeper is reading or hearing recommendations to exceed NSW calcium and pH levels.

A few weeks later what had appeared as very good water parameters with little use of Kalkwasser and buffers now has reduced parameters. Even though they now are about what they are in the wild, they are below what they were a few weeks ago. Must be time for more additives. Right? Wrong! Kalkwasser is added to increase the calcium level back to 450 ppm and increase pH to 8.4. What's wrong with that some ask? Another good question! As noted above, to negatively impact the carbonate system simply raise pH above its NSW level of 8.2. In doing so aragonite/calcite forms as a precipitant, "reducing" available buffers in the system. When this occurs, crystals are forming somewhere in the aquarium. In a couple of days alkalinity appears to be low and it must be time for the buffer. Right? Wrong!

Buffer is added and it raises alkalinity to a higher level. However, in a couple of days pH has fallen to 8.1 and calcium is only 370 ppm. Must be time for more Kalkwasser. Right? Wrong!

There is also a concurrent possibility that coralline growth, which uses huge amounts of magnesium, is decreasing its NSW content. With less magnesium in solution, Kalkwasser increased pH now precipitates calcite and co-precipitates magnesium, further reducing an already dwindling supply of magnesium and carbonates. More crystals are forming somewhere in the aquarium. However, additional Kalkwasser has now raised calcium level to 425 ppm and pH to 8.4. Everything is again looking good. Right? Wrong! In a day or two alkalinity appears to be low and therefore the system must need some more buffer. Right? Wrong!

Bear in mind the addition of "improperly" dosed Kalkwasser masks the systems true pH for a balance between carbonate and pH equilibrium. The more one additive is added, the more it negatively affects the other additive if not dosed correctly! As more and more of these additives are used, more and more precipitates occur, clogging powerheads and turning sandbeds into concrete. Certainly not the fault of the powerheads or the sandbed!

Unless Kalkwasser is dosed correctly, achieving a reasonable calcium level is difficult. Actually, Kalkwasser contains a very small amount of calcium. In fact, at saturation it contains about 160,000 ppm less calcium than does a solution of saturated calcium chloride. Therefore much more Kalkwasser is needed to raise the calcium level and in doing so, pH can be elevated far above NSW level. Unfortunately increased pH can cause the precipitation of the very elements needed to maintain the carbonate system.

Hopefully no one perceives what is said here about Kalkwasser as being negative. It's just that it is mostly misunderstood and/or incorrectly used. If used correctly it is an excellent way to maintain alkalinity.

Testing pH, calcium, and magnesium are precursors to testing alkalinity. They go hand-in-hand like bread-and-butter so to speak. To maintain the recommended alkalinity levels first test magnesium and calcium. Keep them at NSW levels. If you do you'll find that pH will, most of the time, naturally stay at NSW levels, i.e., 8.1 - 8.2."

I would be interested in knowing the brand skimmer you have? If it's poor quality, it could be the systems oxygen content, which has a lot to do with pH, may be quite low. That's why your separate sample looked so low a day later, the dissolved O2 dissipated. Samples of water to be tested for pH need to be tested quite quickly if an accurate reading is to be attained.

Knowing what you have told me so far, I have the following recommendations. First, I'd be darn sure my pH test kit is accurate. In fact, I'd want to check pH with at least two or three different brand test kits. If it's still low, the next step involves the following: Your shimmer "MUST" be very effective, creating lots of tiny bubbles and should be operated on 24/7 basis. A real good skimmer will help raise pH simply because it oxygenates the water, which is one of its most important traits besides removing unwanted pollutes. I would also recommend using a calcium reactor containing a quality brand media (I generally recommend ARM or the Knop brand). Using old coral skeleton material or crushed coral/cheap media is a mistake. Once the skimmer and calcium reactor are properly operating, there should not be any further need for separate additives.

I would also consider purchasing an ozone generator, and Red Sea makes a nice one, even though a little expensive. Look for the one that reads the existing ORP and where you can set the unit to turn on/off as needed. Initially, shoot for a 350 REDOX. Overall water quality should improve and with the help of the skimmer and calcium reactor, pH and important items such as calcium and alkalinity should stabilize and be within correct ranges - calcium 380 - 430 ppm, and alkalinity at about 3.5 mg/l. Keep in mind you only need an 8.0 - 8.2 pH range to have a successful system. Another thing to check is your magnesium level. If there is a large swing between low and high level pH readings, chances are system alkalinity/magnesium level is low. Without sufficient buffers in the system to dampen the swing caused by increases or decreases to carbon dioxide levels between day and night, pH can experience a wide daily range. May not be the problem in your case, but I would still check it and remember, the magnesium level must relate to salinity.

Hope this helps, and keep me posted.

Cheers,

Bob

Dear Bob,

What are your thoughts on algae filtration for the freshwater setup as opposed to the bacterial filtration that is common today? I have heard that in the oceans, rivers, lakes and streams in nature are filtered with algae and not bacteria. If we strive to duplicate nature in our homes (If algae is what nature uses) why aren't algae filters or "algae scrubbers" the norm instead of bacteria based filters?

And if algae scrubbers are so great, why aren't more companies competing to make these things more available to the average consumer. I have yet to see an algae scrubber available for sale in my local fish stores?

Thanks,

Deon

Hi Deon,

This is a method that allows water from the aquarium to flow through an area containing a heavy growth of algae. The algae remove dissolved "inorganic" nitrogen compounds (ammonia, nitrite, and nitrate) and various other elements. Since the algae actually use the nitrogen for growth after reducing it to ammonium, and produce oxygen and remove carbon dioxide during this process, excessive nitrogen can efficiently be removed from the aquarium by simply harvesting excess algae on a periodical basis. This differs from biological filtration where bacteria consume oxygen and produce carbon dioxide while reducing nitrogen products to less toxic forms of nitrogen and finally discharging them as nitrate, an algae nutrient, back into the surrounding waters.

As good as this filtration method may sound, there are some possible drawbacks. Since the algae are housed in a separate container, it is like having two interconnected aquariums. One to contain the algae and one to house the fishes and invertebrate. Not only does the aquarium containing the fish and invertebrate require lighting, the unit that houses the algae must also be lighted. Water flow through the algal scrubber unit must be somewhat turbulent to aid assimilation of surrounding nutrients, thereby enhancing their growth. Even though the water in the entire system may remain nutrient poor when it comes to inorganic nitrogen and phosphate compounds, it may become rich in organic nutrients.

Also, heavy growth of algae compete all too well for the same nutrients that coral zooxanthellae utilize, possibly affecting long term coral growth. The algae also leach organic compounds that result in a yellowing of the water. Colored water affects spectrum and intensity of light, possibly also affecting coral growth. Since the founders of the Algal Turf Scrubber process did not utilize or recommend use of protein skimming, activated carbon, or the use of additives, system results were and still remain a subject of intense controversy. Anyone interested in more information concerning this method should read the "Dynamic Aquaria: Building Living Ecosystems" by Adey and Loveland (ISBN 0-12-043790-2).

Hope this helps,

Bob Goemans

Good morning Bob!

I'm a new hobbyist but I am devouring books, articles and I already have four tanks,(55 gal fish only, 55 reef, 30 gal fish only) and the one with more problems: Is a 375 gal with a 80 gal sump, I have 120 LB live rock and 400 LB live sand, I set it up 2 1/2 months ago, the ammonia is 0, the Nitrate is .0 and the Nitrate is 5mg/l, calcium 420 mg/l, phosphate is .6 mg/l, the alkalinity is 1.8 meq/l or 90 mg/l the pH is 8.6 I think?? because the test kits from Hagen and Aquarium pharmaceuticals you can not tell with accuracy(color results never match the grid).

In the sump I have three divisions. The first a prefilter with bio balls, next to a 20 LB of Miracle Mud with Caulerpa growing under two 15 watts Aquasun, (two types of Caulerpa). Followed by another compartment with more bio balls. Then for the return line I am using a little giant 4-mdqx-sc. Inside the tank I have 4 Rio powerheads 2500. I keep the temperature between 78 - 80 F and I have not set any type of lighting, although in my daylight basement, it receives plenty light from outside and probably one hour of direct light from sun.

I have 2 velvet damsels and one domino damsel. When I checked the parameters the Nitrate level was almost 0 so I decided to introduce a Lion (volitans), and three days later I realize that he had a white spot on the side and was not eating at all. After two more days he was lying on one side and the scales and skin was peeling off, so I took it out and put it in a 10 gal hospital but it was too late. I read Treatment of Exotic Marine Fish Disease by Edward Kingsford, that could have been tuberculosis or a bacterial infection. I read also that if it was tuberculosis probably the whole tank is contaminated. So I decided to put a Yellow tang and three days later I could not resist and bought also a Big long nose butterflyfish. The tang was eating perfect, broccoli, lettuce and flakes, the butterfly never wanted to eat, and suddenly 1 1/2 week later die with no visible marks on the skin. I noticed he was breathing fast, now the tang that was doing fine, is only hiding and he is not eating, he started breathing fast but again with no visual skin problems and the three damsels are growing fast.

I am trying to have an ecosystem without a skimmer, I do not want to fill my tank with chemicals and I am not sure if I need to lower the pH (it has been consistent the actual level), I understand I have to raise the alkalinity and I started to use the reef builder(SeaChem) that I am using for my reef tank, with a dose of 2.5 tsp.. to raise 1 meq/l for every 50 gal, also I am adding reef plus at a rate of 15 ml for every 20 gal, and I am not sure if this is a lot???,, you probably already noticed the series of my mistakes, but I do not, so if you can please help me try to solve why the fish are not doing well I would appreciate.

I am sorry for the length of this e-mail but I try to give you as much information as I could.

Thank you very much for your time.

Filiberto Valero

Hi Filiberto,

Thanks for your interesting letter. Unfortunately I have been overwhelmed lately. Anyway, I presume the other three tanks are doing fine, and if so, the problems mentioned are only happening in the large tank. If so, lets first look at the current status, what system parameters needs to be improved, than at fish health.

Do yourself a favor and get some better test kits! For the price, those from Aquarium Systems will serve you well. Next, the pH should normally fall at night and rise during the daylight hours. Could be a better test kit will indicate that, but please recheck it. As for now, its not something to discuss until I'm sure of its parameters. If this is a fish-only system, alkalinity is not as important as it is in a reef system. What you now have, i.e., 1.8 meq/l is that in natural seawater, so that's not an important fact as of now. So trying to increase it with additives at this time is not needed. Phosphate would be a high if this was a reef tank, but its not. Yet, I would not allow it to become higher or you will be besieged with unwanted algae problems. You may want to consider some of the iron impregnated pads on the market as a way to control it. So, water quality problems that would be severe enough to cause fish health problems don't seem to exist.

Water circulation and oxygenation problems, however, is another story. Keep in mind submerged bioballs are good at the nitrification cycle, but don't replenish the oxygen used as would they if in a trickle filter. Nor do you have a protein skimmer, a tool that not only helps to reduce the nutrient level, e.g., nitrate and phosphate, it also oxygenates the water. Having four powerheads that produce about 700 gallons of flow per hour is helpful, but surface movement and a well oxygenated flow of water (coming from the skimmer) is an important consideration, one that I think you should consider.

As for fishes, most damselfishes are extremely bold and if first in the aquarium, think they own the whole place. They can easily cause enough stress to cause marine ich on most newcomers, especially more prone fishes such as the longnose butterfly. Unfortunately, what you describe sounds more like Tuberculosis. The effects of this malady usually single out one or two fish in an aquarium. Symptoms include loss of appetite, general listlessness, followed by hiding and rapid respiration. Exactly what you describe. Eyes may become clouded and popeye can develop sometimes. Additionally, fins may become ragged, abdomen sunken, and the fish may lie on its side.

Treatment for affected specimens can either proceed in the main tank or in a hospital tank. The hospital tank is a preferred path since it can be treated with two medications, rendering more of a possibility for recovery. If only the main system can be treated, 40 mg of isoniazid per gallon can be used as it will not effect the biological filter, however, all carbon and UV filtration should be temporarily suspended. If utilizing a hospital tank, 40 mg of isoniazid per gallon and 40 mg of streptomycin per gallon can be used. Completely change water every three days and re-medicate. If possible, feed medicated foods. Do not return fish until there is a complete recovery.

Caution, as fish tuberculosis (Mycobacteria marinum) can be transferred to humans when an aquarist places an open wound on their hand or arm in the same container holding the infected fish. A very possible result is that open lesions will develop into abscesses that won't heal. Antitubercular drugs isoniazid and streptomycin are needed to cure the problem, as penicillin is ineffective.

I hope this is helpful.

Bob

Hi Bob:

I know you're the best informed when it comes to NNR filtration so I decided to write you (besides I always read your column in FAMA). I live in Mexico and owned freshwater aquariums for about 10 years. I then left the hobby for a few years, but now finally want to get started again.

I'm going to start with a 36''L x 15''H x 10''W aquarium. This will be a freshwater tank with 30 Paracherodon axelrodi and 4 Microgeophagus ramirezi and a lot of plants. I'll use a plenum as its main filtration system (I think I'll be the first in Mexico to use it in freshwater tanks). I can't find any reason not to use it in freshwater tanks, besides I think this is the way the rivers work in nature. I'm also going to document all the processes. I'll use 3 - 5 mm silica gravel for the plenum, and also use AZOO plant mixture. The layers in the plenum will be as follow: 1.75 inch for the first layer, then anti-dig mesh, then 1.25 inch for the second layer and finally .5 inch for the plant mixture. Could you tell me if these measurements for the layers and gravel are corrects? By the way, for the fish selection the temperature should be maintained high, but I read that the denitrifying bacteria might be affected. Is that correct?

As for the cycling stage, which I estimate will take 10 weeks, I plan on using raw fish flesh to help the cycle along. There's an inexpensive eatable fish here in Mexico called "Charal" which I have used in the past to feed Oscar's and other big fish. This will help create nitrifying/denitrifying bacteria in the gravel. I'll also use for biological filtration sometime during the cycle, probably in two weeks, a new Biowheel filter, Fluval 3 canister filter and a UV.

I think all the nitrifying bacteria will go to live in the Biowheel, and the denitrifying bacteria will remains in the gravel. I read an article that says that Biowheels or wet-dry filters are not compatible with the plenum NNR. I don't think so, because there are different kinds of bacteria in the different parts of the aquarium. Anyway could you tell me if it's true?

Thanks a lot for your help.

Raśl Antonio Aguilar Castillejos

Mexico

Dear Raśl,

Thanks for the kind words, and over the past ten years, numerous freshwater aquarists have tried plenum systems in various types of environments and all have reported good results. In fact,, a lady who had a large failing goldfish tank installed an interconnected plenum system and just raved about the extremely positive results it had on fish health in its first six months of its use. And those that had plant tanks, such as you're planning, noted that even plant growth appeared to be positively impacted. Some came back a year later and said they could see some plant roots in the plenum itself, and these plants were in super excellent condition. Cichlid users also raved about the reduction of nutrients with plenum usage, and even Discus users were happy with their results.

Actually, the plenum method is an improvement on what Mother Nature provides in the wild. That's a long story, but fully explained in some of my booklets, and of course in past articles in many different magazines. And if you want more detail about those improved processes, visit my website and go the 'Guest Articles' page and read the two-part article titled "Sandbeds" and Julian Sprung's article.

As for the chosen substrate media, it's perfect. And if there will not be any fishes in the system that would cause major intrusions deeply into the substrate, I would skip using the dividing screen. Also, use the same size substrate throughout the entire bed. As for the temperature range and other parameters mentioned, don't concern yourself with these details. Even if your bulk water temperature range falls into the mid eighties, the needed natural parameters for the plenum process to function will still occur, and, could be they might even be slightly accelerated. However, it's a fact plenum sandbeds run slightly cooler than the bulk water temperature, however, just the opposite is true for deep sandbeds directly on the aquarium bottom.

As for start-up, it will take at least a couple of months to get the nitrification cycle up and fully functioning. To help speed that up there are many pre-bottled starter solutions on the market that can help accelerate the microbial processes/the nitrification cycle. I would recommend one of those instead of any raw fish flesh being placed into the aquarium, as raw fish flesh can easily transmit diseases/unwanted pathogens. As for the bio-wheel, it is one of the most simplest and efficient forms for providing a nitrification area and some oxygenation, and has been used in aquaculture for many decades. And as for a trickle filter, the same is almost true, however, in the aquarium industry it has not been around as long as the bio-wheel. Anyway, either form of "filtration" would not be advisable in conjunction with a plenum system in "marine" aquariums. Yet, in a heavily planted freshwater tank the additional nutrients dumped into the bulk water from this type equipment would not impact the overall system, and might prove useful, as this aquarium will contain many plants.

As for the different classes of bacteria, the nitrifying bacteria will live wherever there is an ample supple of dissolved oxygen. That will be on any surface area (including the sides of your fish), in the top one inch of substrate, and of course the surface of the rotating bio-wheel. The denitrifying bacteria, which consist of two different classes, will occur naturally (without any help from you) in the deeper depths of the substrate.

I also suggest that once the system is established you start adding a small amount of brown sugar or unprocessed honey once per month. Since you have a small aquarium with quite a few fish, this will help feed the nitrifying bacteria that use ammonia/ammonium as fuel, thereby preventing any possible nuisance algae from forming. As for how much, one-quarter of a teaspoon would suffice for your tank. Keep in mind table sugar does not have the same carbohydrate value because of the bleaching process, as do these unprocessed sugars.

And last, do not begin use of the UV until the nitrification cycle is complete.

I hope this helps and keep me posted,

Bob

Dear Bob,

I have been an avid reader of your columns in various magazines, web sites etc. for some time now. Have been keeping a reef aquarium for about two years now. I have a six hundred litre aquarium (400 litre display, 200 litre sump). Have eradicated algae problems in the past (mainly hair algae) through various articles found through your site. My tank has been doing really well, until suddenly a rust coloured substance has started appearing. My filter wool (presump filter) turns from white to orange brown in a matter of hours. I change this on a two-day basis. My skimmers produce an almost brown gunk, mud like substance, and wherever my circulation pumps blow in the aquarium, this rust coloured "algae" appears.

For filtration, I use 1/3rd visible volume live rock in the tank. In my sump start off with filter wool, followed by a skimmer which is constructed from PVC, with a 4000 l/hour pump, followed by a continually lit refugium, housing some Caulerpa (mostly racemosa) on a crushed coral bed, followed by a small queen protein skimmer (2000 lph), followed by a 15 watt U.V. sterilizer, followed by ROWAphos in a fluidised filter, then returned to the tank. I change about 25% water every month, using water from our local Aquarium (two oceans in Cape Town) which i run through my U.V. steriliser for a couple of hours before adding to the tank.

Water parameters: