BB vs. DSB

[inwall75]

Originally Posted by Covey

I was under the impression that the last "poop" in the chain was the bubble of nitrogen bubbling out of the system. There doesn't seem to be any magic involved as the system seem to be working the how the Nitrogen cycle is suppose to. Your "closed system" are open in a way in that we allow gases to escape from them. There is no major violation the the law of conservation.

Yes there is under that thought. The problem is that there are MANY cycles going on in our tanks. How does the Carbon leave? How do the phosphates leave? The Nitrogen cycle can turn NO2 into N or 2 Oxygen molecules. NO3 can release N or 3 Oxygen molecules. (This is highly simplified). While they can leave, what about the "left-behinds"?

[Covey]

Water changes,chemical media, refugiums, and skimming. I guess I am a not DSB purist. The left behind really don't matter as much. Okay phosphate does but it can be removed by the methods above. Carbon, quite a few reefkeeping methods have you dosing carbon. Too much carbon isn't going to kill anything. The nitrogen on the other hand is very dangerous. At low levels it will brown out acro and at still farely low levels it will start killing SPS. That is my major beef with BB. Sandbed are very effective at removing nitrogen from the system. You remove your sandbed and you remove an excellent backup for your reefkeeping practises. BB seem to be pushed by a small well known group of veteran reefkeepers. Their tanks are beutiful. There also well maintained and set up. The problem is they seem to sell this to the masses. Reefkeeper with niether the talent or the means to pull one of those beutiful BB tanks off. More often than not it seem that the bare bottom crowd has chosing to run systems with Nitrate levels up around 5-10ppm. Levels of nitrate undetechatable by hobbiest grade test kits are easily opptainable with a sandbed.

It seem to me your trading a "sure thing" for a "might be better with more work".

[inwall75]

Here's the main problem. Most people have never run a Berlin system with higher flow. I don't have Nitrate problems in my BB tank. I don't have Nitrate problems in my DSB tanks either.

The Carbon is an issue because most people don't know how SPS really works. The bacteria in the sandbed sink the Carbon too. Most people are amazed when they go BB at how much more stable their alkalinity levels are. Remember, alkalinity is CARBONate hardness. A lot of people concentrate on maintaining higher than healthy levels of Calcium making it difficult to maintain proper levels alkalinity. I don't understand why this is done because the carbonate is just as important in maintaining healthy growth. When people go BB, they tend to see faster growth because the carbonates are more available.

BB is also not more work. Twice a week I get my arm wet and suck up detritus with a turkey baster. That is roughly 5 minutes of work per week. The main difference between BB and DSB is that with BB you do a little work per week whereas with DSB, you don't do that weekly work but simply save up all that saved time and then spend an entire weekend pulling a disgusting, smelly, sandbed every 4 or 5 years. I really don't think people are saving time anyway. I have not dealt with diatoms, cyanobacteria, dinoflagellates, dirty sand, hair algae, etc. in my BB tank but I have with my DSB tanks.

Please don't misunderstand me. I'm not against sandbeds and I'm not trying to convince you to change. You can keep your SPS tank however you want. After all, it's your tank. As long as you understand that your sandbed isn't some magical thing that makes matter disappear, that it only exports Nitrogen and Oxygen, then you're good to go. Then you know that at some time in the future you'll have to pull and replace it because anything that isn't Nitrogen or Oxygen is just slowly filling up the bed. Once it fills up, it starts spilling nutrients into the system and when keeping SPS, that is called a sandbed crash.

Water changes,chemical media, refugiums, and skimming. I guess I am a not DSB purist. The left behind really don't matter as much. Okay phosphate does but it can be removed by the methods above.

On a sandbed that is fairly young, none of these methods will do anything to the phosphates or Carbon that is now cycling in your sandbed. Remember, these bacteria are programmed that if Carbon/phosphates/sulfates/metals etc. are available, grab as much as you can and then reproduce. They don't give these nutrients up unless they have to (as in, when the bed is filled up and it is now scewed to be largely anaerobic). If you need Phosban or Rowaphos in your SPS tank, then you need to replace your sandbed or you are overfeeding or your skimmer is not good enough for your tank. Waterchanges do little to remove phosphates as bacteria are very quick and bind them up in their bodies and sink them in their biofilms. Again, that's why you cannot normally test for phosphates. If you can get a reading of them, your SPS are in trouble. Chemical media and refugiums mainly exist to make up for inefficiencies of filled up sandbeds.

BTW, if you get Dr. Shimek to come over here and read this thread, have him explain the following.

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Having a 60 gal remote DSB may work, some folks can pull it off. I suspect, however, in most cases these turn into nutrient-sinks and will be problems in the long run.
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It really matters because that is why a sand bed works. The material once captured by the animals in the bed really never leaves the bed. It cycles over and over in the bed from one organism in close proximity to another until the energy in it is used up and the material in it gets exported. The decoupling of these reactions allows the material to be liberated into the tank water where it will be food for, primarily cyanonbacteria, but other microalgae as well.
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As an example of the flow necessary to move materials out of an "Acropora" thicket in nature, the flow across such a region has been measured, In the volume of a 100 gallon tank, that amount of flow would be on the order of 50,000 gallons per hour....
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heres a good one on your will last forever quote

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The added feeding goes to maintain the DSB that would have been adequate if it were in the main tank. However, in this case, you have added more nutrients to the system and as the DSB is a finite system it becomes saturated and will not be able to export them adequately.
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when asked what kind of tank a dsb would support

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There is no magic number per gallon, but the actual number of fish per unit volume is pretty low. Probably on the order of no more than 3 or 4 relatively small fish per hundred gallon volume. Similarly coral diversity and abundance is pretty low.
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but he does let us know its simple

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If the hobbyist can't maintain a DSB in the main tank, which is about as easy as falling off a log, they shouldn't really try to maintain one in remote tank, but should probably try to use some other sort of filtration.
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but then 4 days later

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It is interesting that people tend to think that all of this is supposed to be "simple" and "easy" to do. Most folks don't realize that a coral reef ecosystem is the most complicated ecosystem on the planet, and that the sand bed component to it is also complicated. The level of complication is here is orders of magnitude more than is found in any manmade object, structure, or construction.
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oh here is one on the skimmers

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Yes, indeed. Then I did the research to show I was incorrect about skimming - A point I noted in presentations as well as in print.
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oooppps

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Personally, if I was culturing corals for reproduction I wouldn't use a sand bed.
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When asked how many detrivores to add to a DSB Ron says

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The maximum amount of the most you can maintain.
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but then 2 days later in the same thread

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In my advice I generally tell people to add as little as possible, as that is the cost effective way.
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Heres a little help for folks on what and how many kinds of critters you need

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A DSB needs around 200 species to function properly and most land-locked reefers can't get the diversity high enough with just the detritivore kits and seeding with "live sand". The "Southdown and Seed" method is quite common and I doubt many of these tanks ever reach the diversity level required to function as envisioned. A DSB can be handicapped right out of the gate by lack of diversity.
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This Paragraph was removed by poster as it wasn't necessary...Curt

I don't want you thinking he's a bad guy. He's actually quite nice and intelligent. However, he's a worm and bug specialist and when it comes to them, he's a freakin' smart. When it comes to sandbeds, he already has an interest in worms and bugs so when he read Adey's work I'm sure he was thrilled. Then he tried to make money off of it to his undoing because he didn't do enough research. He's changed his tune completely at this point and now tells people with cyanobacteria problems to pull and replace their sandbeds.

[Covey]

I am going start trading with a local BB reefer. Hardily scientific, but it should still yield some interesting result like 6 months from now.

Originally Posted by inwall75

The Carbon is an issue because most people don't know how SPS really works. The bacteria in the sandbed sink the Carbon too. Most people are amazed when they go BB at how much more stable their alkalinity levels are. Remember, alkalinity is CARBONate hardness.

I am interested in bunk either way and that one alway got me. "Sand Bed supply calcuim and other minerals to support the needs of your tank." Pure bunk. Lets see. Argonite doesn't dissovle until the pH is below 7.8 or lower. Natural pH levels are around 8.2. So how is it going to supply calcium. I don't know about the bacteria sinking carbon but I have read that it was that army of other sandbed creatures using the calcium, carb, and such. Splitting hairs but anyway. That is one BB thing I buy. I seen people there Cal/alk demands dropping by around a third after the switch.

[inwall75]

Originally Posted by Covey

I am interested in bunk either way and that one alway got me. "Sand Bed supply calcuim and other minerals to support the needs of your tank." Pure bunk. Lets see. Argonite doesn't dissovle until the pH is below 7.8 or lower. Natural pH levels are around 8.2. So how is it going to supply calcium. I don't know about the bacteria sinking carbon but I have read that it was that army of other sandbed creatures using the calcium, carb, and such. Splitting hairs but anyway. That is one BB thing I buy. I seen people there Cal/alk demands dropping by around a third after the switch.

Every, and I mean EVERY, living thing on this planet contains both phosphates and Carbon. (If something was once alive and is now dead, it still contains both). The important thing to remember is that neither disappear. It might move to another life form but it doesn't disappear. Some critters need calcium as well to build exoskeletons. Normally we think of crabs, lobsters, etc. when thinking of calcium exoskeletons. However, bacteria need it for their exoskeletons too. Sure it's in small amounts but in a sandbed, there are tons of bacteria.

That is where both the Calcium and Carbon is going....to the bacteria.

[Matt Rogers]

Ok. I just read this whole thread and you guys both deserve a prize for exchanging your beliefs in a civil way. Seriously!

Thanks for not deviating too much on Dr. Ron. Like Inwall says, even if you don't agree with him, he's been a stand up guy on the 1 to 1 in my experience. So thanks for staying on topic - BB vs. DSB.

It's threads like these that make 3reef a cool place to hang out. I've learned a thing or two for sure and that's what it's all about. Thanks guys.

[Blade_Runner]

Wow, this has developed into a great thread.

+1 on Matt's assessment.

How about a Karma prize.

[inwall75]

Originally Posted by Covey

Hey Inwall do you have any links to the "Sandbed as a nutrient sink" type links I would enjoy some more reading.

OK....I'm getting ready to move and I'm finding it difficult to read through all of my links to find ones that would make sense to most reefers. Here are a couple quotes and I'll also give you a link to a 43 long page thread with tons and tons of abstracts and links.

Phosphorus removal in a marine prototype, recirculating aquaculture system by Barak, Cytryn, Gelfand, Krom, Rijn that was published in Aquaculture 220 (2003) 313-316[/quote]

ABSTRACT: High concentrations of total phosphorous and low concentrations of soluble orthophosphate were measured in the intial stages of sedimentation under oxic and anoxic conditions, suggesting that most of the phosphorous was associated with organic matter. Depletion of oxygen and nitrate in the sludge layers of the sedimentation basin coincided with sulfate reduction to sulfide and a release of soluble orthophosphate.


Here's a good summary which I'm actually copying from Joe Burger (JBNY).

nitrifying bacteria absorb PO4 when consuming nitrates. As long as there are nitrates in the system they continue to hold their absorbed phosphate. But when nitrates are unavailable, or at a point that is very low, the bacteria start to release phosphates back into the system. They even refer to a study that found "that phosphate release in soils derived from aquaculture ponds ceased upon addition of nitrate and acetate."

Full article is here. http://www.cnidarianreef.com/posted/PO4_removal.pdf

'Recycled' nutrients released from the sediment during the decomposition of organic matter constitute an 'internal nutrient load'. Benthic recycling of nutrients can be an important component of annual nutrient budgets in some coastal waterways.

Nitrification is inhibited when sediments are anoxic, and this can cause a lowering of denitrification efficiencies. Under such conditions, relatively less nitrogen may be vented to the atmosphere as N2 gas, and relatively more nitrogen may be returned to the water column as ammonium (unless denitrification is coupled to water column nitrate).

I'm sure the last quote has people scratching their heads. Not only is anaerobic bacteria not turning everything into Nitrogen gas, they aren't the ones doing it, and the ones doing it are periodically performing ammonification as opposed to denitrification. To make matters worse, the ammonium is being released back into the tank. Denitrification is NOT occurring deep in the bottoms of our sandbeds, it's actually occurring at the aerobic/anoxic interface. http://www.ozestuaries.org/indicator...trients_f.html

I hope that people learn to question in their own minds things that people say. Just think through it. Most of this hobby is truly common sense. If you don't know what to think, Google is your friend. There is still a quite famous person who tells people that matter turns into energy and disappears. This individual confuses Trophic Energy with matter and thinks they are interchangeable. While it is true that there is a possibility of matter turning into energy (google nuclear reactors or atomic bombs), I DEFINATELY hope no one has that occurring in their tanks. That might explain why this person hasn't been able to keep a sandbed for more than a couple of years and keeps blaming other factors for that individuals repeated crashes. In this case, I don't mean a crash whereby SPS brown and go through STN or RTN, I mean his tanks repeatedly get nuked. Hmmm...maybe that persons tank did have a nuclear reactor in the sandbed. That would explain a lot.

I also have a request from people reading this page. Please don't tell other people how they HAVE to run their tanks. This issue gets contentious because people are finding out that not everything works the way it was previously advertised. Ok, fine. Get over it. There is still merit to DSB filtration as long as you understand it. If you read some of my comments, you know that sandbeds can give new people a false sense of security regarding their feeding habits. You can run a DSB a loooong time if you use intelligence when stocking, feeding, types of flow, and efficient skimming. A DSB can be useful.....just don't use it as a crutch to continue maintaining your tank poorly.

[corebond]

A very informative post. Thanks

[Monacle]

will vacuuming the sandbed every once in a while prevent these meltdowns? Actually, I need to know about something. I am starting a breeding operation and I have 32- 20 gallon tanks and I want them all to be independant (not sharing water and filtration) but set up identically. I was going with a plenum. My description of a plenum: A dead air space under the sandbed made with plastic ceiling grid suspended on top of half inch pvc on its side with plastic mesh screen over the top of it doubled. Then the live sand goes over the top of this about one half to one inch thick. I let the live sand do its thing for a while then I top over it with 2-3 inches of aragonite. Then I put 1 nice piece of LR in the tank two corner filters. (these are the little box filters that operate with an airstone.) The reason for two is that when you change the filter media in one it doesn't throw the system out of whack because you only change one at a time. Then I was thinking of adding a snail or two and a herm or two. I would like advice on which you all think is the best snails and herms for this type of system also. And last but not least I would like to put an appropriate anenome in each of the clownfish breeding tanks. I know this post strays a bit from the topic, but my main question is: do you think the sandbed is a good idea for this setup and should it be vacuumed every once in a while??