BB vs. DSB

Discussion in 'Sand' started by Covey, Dec 5, 2005.

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  1. Covey

    Covey Scooter Blennie

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    Well we have danced around the issue for sometime here on this board but I thought I would just bring this out into the open. This is a discussion board after all and we seem to be skating the hottest topic available to the sand board. Basically sand or no sand. Bare Bottom versus Deep Sand Bed method.
    First of all I would like to point out that this discussion is anything but new. Sand beds as a method can really be traced back to 80's with the introduction of the Jaubert Method. Bare Bottom is just as old because with very few changes it is basically just a recycled version of the Berlin Method. In the 80's and early 90's the Berlin Method ruled and then people started switching over to keeping sandbeds. Now there seem to be momentum headed back the other direction. I have only been keeping a reef for little over a year now and many other newer people seem to pile into the discussion so I just wanted to point out that this is nothing new.
    My bias, well it would only be far to disclose what I think before making you read this rather long post. I like sandbeds and had thought of switching to BB but decided to leave it. I researched switching and got a better understanding of BB and since I seem to be a moderate on this issue I thought would be a good one to get this discussion going.
    I thought simple definitions of the two methods would be helpful as well. The "Deep Sand Bed Method" has been evolving since the introduction of the Jaubert method but the most up to date mainstream opinion at this point seem to be to run a 4" deep bed of 1-2mm grade sand works well. You add the sand to the tank during setup. It may take 2 weeks to month for it to cycle but once you start to see nitrate bubble coming out of the sandbed your set. Some thing even with in sandbed keeping are debatable but to the best of my knowledge the sandbed does its best taking care of itself. You should not vacuum it and the "sand bed cleaner critter packs" are mostly a bad idea. The vast majority of the creatures you need to maintain a sandbed are microscopic hitchhikers you will get free on your live rock. So set it up and leave it alone.
    Bare bottom. As the name implies no sand. Many people have started using Starboard, a plastic cutting board as a substrate in order to add some insurance against a rock side breaking your tank. Starboard is neither needed or particular harmfully in anyway so that is your call.
    Basically this is where the big different in the methodologies show up. In DSB detritus in the system that makes it way to the sandbed gets processed by the sandbed. The bacteria and micro infauna that maintain the sandbed break down the the waste products hopefully all the way down to nitrogen gas which bubbles out of you system. In BB instead of a biological method for breaking down detritus a mechanical method for removal are employed. Basically you add enough water movement that the detritus staying suspension in the water until it is removed from the system by a filter sock and then by a powerful skimmer. Waste processed in the tank versus waste removed from the tank before it can degrade.
     
    Last edited: Dec 5, 2005
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  3. Covey

    Covey Scooter Blennie

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    Why am I keeping my sandbed. I am a SPS keeper and I have seen many awesome looking BB tank. Usually too photos are included with "the my tank never look better" and "sandbed suck" comments. Many people have claimed to see a night a day change in there reef when they switched from DSB to BB. Here is the problem I have with this comparisons. They are wholly and totally unscientific. The best reference I have seen is this thread http://www.reefcentral.com/forums/showthread.php?s=&threadid=650985
    If I were to go BB I would follow this very well though out and written plan but it gets me back to my original beef with BB. If you change a half dozen variables in your reef ,3x bigger skimmer, massive flow increase, adding ozone and UV, and above all else a now attentive active reefkeeper you CAN'T claim the sandbed was the cause of all of your problems. There is just no way you can creditable claim the sandbed was causing your problems. Even if you only cooked your live rocks and added them back to the tank you have changed a rather large variable. I have done a rather heavy rock scrubbing to get rid of my hair algae on my rocks. Including blasting rocks off with a powerhead. I removed like 20g of filth from my reef. The health of my reef improved dramatically in 2.5 hours. If I had removed my sandbed at the same time I could have gotten the impression that my sandbed was a curse. I changed one thing at a time so I know that is not the case.
    What I have learned from BB I still find useful. To do right by your SPS you need to run a nutrient poor system. Almost all the important upgrades from "going bare bottom" can be done while still leaving the sandbed. I have upgraded my skimmer and upgraded my flow. 29X right now more in the future. With the new high flow low speed pumps it is not that difficult to crank the flow way up without disrupting the sandbed.
    I went that far why not go "all the way". Bare bottom require extra powerheads to keep the detritus in suspension(Ugly). It requires extra maintenance in the form of siphoning what detritus doesn't make it into the system. The sandbed basically takes care of itself. It can be a desert or jungle. In that if I require it not to do much the levels of biological activity takes care of itself. In a nutrient poor system it is not asked to do much. At one point I was using ammonia loaded RO water as top off. My sandbed fired up before I figured out what was wrong. Nitrate just bubbled out of my substrate. I was dosing ammonia daily into my tank and I had ZERO nitrate. My parachute, I mean sandbed was saving my tank. I see why some people setup bare bottom but I just don't see any reason to remove my sandbed.
    I have tired to keep this thread friendly and I am hoping to have a decent discussion. Please save the flames either way for an another forum. So what do you think?
     
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  4. inwall75

    inwall75 Giant Squid

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    Wow, that's a mouthfull. :)

    Let me startoff by saying that I run some BB systems and I also run DSB systems so I don't want anyone getting their underwear in a bunch if they don't like what I say.

    Well you are certainly correct that scientific methodology requires that only one variable is changed so you can confirm causality. However, going to a BB does not require that you cook your rocks. However, it makes your job easier as you will not need to siphon as much detritus if you do. Most people who've yanked out their sandbeds because they want better health for their SPS, have LR that is loaded with detritus and phosphate as a result of their rock that is sitting on their sandbed. This is bad for SPS. Have you ever seen pics of people's SPS that are RTN'ing from the base up as opposed to from the tips down. That's usually an indication that their rock is loaded.

    The term sandbed "crash" doesn't mean what most people thinks it means. To most people, they are assuming a Hydrogen sulphide pocket nuked the tank. In reality, it was a term that SPS keepers used when their sandbeds filled up and started spewing phosphates into the water column. Since phosphates inhibit calcification and cause SPS brownouts, that is a bad thing. The annoying thing about sandbeds is that there's no way of guaging when it's going to fill up. What would be considered a "crash" in a SPS tank would not be considered a "crash" in a softy tank as softies can handle phosphates quite well (actually, they grow faster). Additionally, DSB's prevent the amount of circulation necessary for the good long-term health of SPS. If you had that much detritus on your rocks, I would suggest adding more water movement equipment or re-arrangement of your current powerheads. BTW....detrial mulm is a major cause of algae problems. Your post indicated you had hair algae and a lot of mulm so you might want to increase circulation for algae control as well. For the reasons listed above, I'm not in favor of DSB's in an SPS tank.

    Actually it doesn't work that way. Nitrifying bacteria are very quick. The most dangerous form of N is Ammonium, the second most dangerous form is Nitrite. You don't need a sandbed for that. Your LR will take care of that quite easily. It will also do quite a bit of denitrifying for you as well but that is a slower process and takes longer.

    I'm not about to read that huge thread. I doubt anyone else will either. For purposes of explaining what is happening, let me throw out a quick and dirty explanation of some of the things going on in LR and a sandbed so everyone is on the same page. That way a good discussion can develop.

    The cool thing about algae, is that it tells you where your primary problem is. If you have hair algaes and/or cyanobacteria on your sandbed but none on your LR, that's where your problem is. Have hair algae on your rock but none on your sandbed, that's where your primary problem is.

    What happens is that LR and most sands are made of CaCO3 and phosphates naturally adsorb (chemically bond) to it. Then the good-guys that perform Nitrification for us engage in their 'bad habit'. Their bad habit is that they always want more phosphates (P) than they currently have. (It's a survival tecnique....they have to have enough P for themselves and for their offspring when they divide). They don't have mouths so they use acids and enzymes to literally dissolve the P right off the rock and sand. Unfortunately, bacteria measure their lives in hours, not days or years. Once they die, any P they contain becomes bio-available to other bacteria, re-adsorbing to CaCO3, or food for algae. (Luckily, it's usually other bacteria). This is why it's usually impossible to test for P. Only after all other sinks are 'full' can P be tested for in the water column.

    Have you ever turkey basted your rocks and thought to yourself, "There is NO WAY that my fish have pooped that much on my rocks"? You would be correct. This detritus is produced by the bacteria that live on/in your rocks and if you don't have sufficient flow, you better be turkey basting your rock so your skimmer can remove it as it is supernutritious for algae.

    You never see posts like, "I can't stop hair algae from growing on my powerheads". Even though there are the same bacteria there and they also die and release P, the quantities of bacteria are MUCH smaller because they can only live in a biofilm on the surface. Additionally, powerheads are smooth and it is much harder for an algae spores to attach (unlike LR).

    Just like the Nitrogen Cycle, the Phosphate Cycle is going on 24/7. If you don't want algae problems, it is imperative that one minimizes P inputs and maximizes P exports 24/7 too. Waterchanges are great at removing Nitrates but they really aren't all that effective at removing P.
     
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  5. Diver_1298

    Diver_1298 Eyelash Blennie

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    Very Interesting Discussion!! I have enjoyed reading this and I believe I actually understand most of it. :) I Don't have strong feelings one way or the other about a bb or dsb. But I understand some of the reasoning NOW, behind some peoples tanks and how they keep them up. Thank you once again for an interesting read.

    Jim
     
  6. inwall75

    inwall75 Giant Squid

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    Thats the whole purpose of threads like this. So that people understand what's going on in their tank.

    I answered a question to someone on another board who pulled his sandbed and expected his phosphate problem to disappear. It didn't get any better and wanted to know why. It turned out that he had a 1/4" of detritus in his sump the entire time. His sandbed was probably fine as his tank was only a year or two old.

    Sandbeds have some disadvantages and some disadvantages.

    Advantages

    • If you travel a lot for work, the sandbed will sink (store) detritus so it doesn't rot in your water column.
    • A properly maintained one is attractive.
    • It's a great phosphate sink and can make up for newbies tendency to overfeed.
    • If properly set up you will get NNR (Natural Nitrate Reduction) from it. It doesn't really do what Dr. Shimek claims it does as much as most people think. What really happens once the sandbed is not new is Ammonification. Very little of the Nitrates burn off as Nitrogen gas. Most of it goes back to Ammonium. Here's what happens: Ammonium to Nitrite to Nitrate and then back to Ammonium. However, the end result is the same, low Nitrates in the water column. The ammonium only becomes a problem when the bed is filled up because Ammonium is a natural fertilizer.

    Disadvantages
    • They give a false sense of security to newbies. They think that because they are not showing high Nitrate readings, they are not overfeeding.
    • There is no way of determining when they will start releasing phosphates and ammonium back into the water column. (However, cyanobacteria that cannot be beat with more circulation is a clue).
    • Certain corals need more circulation than sandbeds will allow
    • Hydrogen Sulphide pockets can form in anaerobic areas which is dangerous if disturbed.
    • If there is a power outage, the bacterial respiration causes Dissolved Oxygen in the tank to drop much more rapidly than a BB or SSB tank risking fish lives.
    • You don't have a way of controlling biological processes.

    One major disadvantage of BB is that if you travel a lot, it's hard to siphon up your dead areas. I've found that no matter how good you design your flow, there is always somewhere in your tank where detritus pools. You don't want to let that rot in your tank as it will release phosphates and Nitrates.

    SSB's have the same advantages and disadvantages as DSB's but because they are shallower, they fill up sooner. For shallow sandbeds, I typically recommend using a gravel cleaner and cleaning with each weeks water change rather than using it for NNR. Removing the detritus is just as good as letting the detritus rot and then be processed by bacteria.
     
  7. Covey

    Covey Scooter Blennie

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    My very public algae battle had next to nothing to do with anything going on in the tank and was caused by my 3ppm Chlorimine level in my tap water. Chlorimine>Carbon>Ammonia>RO>still Ammonia. Added 2 stage DI problem solved.
    And yes I am adding more flow SPS keepers are always adding more flow. waiting on the vortechs to come out.
     
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  9. inwall75

    inwall75 Giant Squid

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    Bummer!!!

    I'm glad you pointed this out because so many water districts are converting to chloramines as opposed to chlorine. IMO everyone should call their water company to find out if they have converted or are getting ready to. This is a new problem for reefkeepers that many people don't know about.
     
  10. Covey

    Covey Scooter Blennie

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    Actually it does work that way. A sand bed has a far larger surface area than LR ever will and rest asured during the dark days before I fiqured out what was happening the sandbed was bubbling like someone buried a airstone in it.

    I've seen the SPS BB bottom tanks on-line with huge turnover numbers. Like a 100-120X plus and thought to myself I probably couldn't swing that in a tank with sandbed. Then I started to see BB tank in person and realized that much of that monster flow was dedicated to BB maintainance. Not flow for the corals. Example a friend of mine runs BB. He has 2 streams, a return aimed to give his corals flow. He has an additional 6 maxijet keeping his detrius in suspension. Those powerhead are always counted in this the total turnover but never do anything for the coral.
    Most SPS we keep are high light SPS. Their also typically the corals that need the high flow. As a result most of them are put high up into our reef tank. Table acros have some of the highiest flow requirement. It is farely easy to pulse a Stream and the table acro. The table will love it and it is very unlikely you will ever move any of your sand. You can add a ton of back and forth movement into the top half of your tank without stiring up the bottom half of your tank. All it takes is setup.
     
  11. Covey

    Covey Scooter Blennie

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    My tap is Mississippi river water I understand the need for the chlorimanes even is I don't like it.
     
  12. inwall75

    inwall75 Giant Squid

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    BTW....great thread and info Covey. Karma to you. :)

    I was very unclear in my post. I always know what I want to say but sometimes my fingers don't cooperate. :( I was pointing out that the Nitrification process is extremely efficient and does not require a sandbed. The Berlin method was adding LR to a BB tank with a piece of crap skimmer (by todays standards). Once they did that it was found that they no longer had difficulties with Ammonia or Nitrites. While Nitrification was fine, denitrification was a different story because that is a slow process that requires interaction between anoxic and aerobic conditions. LR does this but not very quickly. Water changes were a large portion of taking care of Nitrates then. In later years, this slowness of processing Nitrates was handled differently by different people. Some people increased flow so the detritus did not break down in the tank and eventually cause Nitrate problems. Others put sandbeds in their tank to temporarily sink nutrients.

    That's an awful lot of powerheads....yikes. I certainly don't need this. That must be a massive tank. However, BB maintenance is the same thing as feeding the corals. Detritus covered with bacteria is a favorite food of SPS.

    While that is certainly true, the sandbed will fill up quicker as most of the detritus will be processed by the sandbed as opposed to being removed by the skimmer.

    While I prefer BB for my SPS tank, you can most certainly have a DSB system with SPS. You can also do what Steve Weast does. Basically his entire sandbed is vacuumed out and replaced 4 times per year. You can put a sandbed in there, allow the nutrients to sink for a good number of years and wait for slowed SPS growth and colors browning out, and then pull the sandbed and do one major export like replacing replacing Phosban or Rowaphos. A sandbed is truly a very efficient phosphate sponge (at least temporarily). Google "phosphate cycle" and you will find that ocean sediments is a major component of it.
     
    Last edited: Dec 6, 2005
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