Put the gloves on and let's talk DSB.

[ReefLady]

Somehow I missed the part where they began to fall out of favor. As a shameless discussion starter, I'd like those more knowledgeable than myself in the subject to enlighten us.

I'm starting to get paranoid. A friend and recent tank of the month, Steve Miller, (http://reefkeeping.com/issues/2003-09/totm/index.htm) just had his tank crash. His caps were the first to go, followed by just about everything. He said he found what looked like rust-colored buildup in his activated carbon media, even encrusting the actual carbon. He said he also found it on his LR in areas where it was submerged below the DSB. He was thinking metal contamination, but doesn't know where the metal came from.

Another thing he mentioned, was that he has been aware for some time that his sandbed was severely lacking in life/diversity.

His tank was up for about three years I believe, which seems to be the common time frame for bad news.

Do we blame this crash on the DSB?

Do we know what warning signs to look for?

Do we know how to avoid such a catastrophe?


Just a few of many questions I have on the subject, hopefully a nice discussion will follow that will help me understand all of this.

Travis

 

[Craig Manoukian]

My tank, and only reef experience, has been set-up about a year and a half so I have no experience on this issue.

It is worth keeping in mind that no two tanks are the same and so we can only talk in generalities. Rob Toonen has a tank that is going strong after 16 years.

For example, the source of metals could be leaching from the LR in your friends case, but that doesn't mean, even if true, that all tanks with LR will suffer the same fate.

Great topic, as it effects the vast majority of reefers, including yours truly.

:smirk:

 

[Maxx]

Wow Travis,
Sure you don't wanna discuss politics, religion or gun control instead? This one is sure to cause some disturbances and passionate discussion. I'll begin by stating my preference and why I reached that conclusion...then I'll begin to smother all who oppose my view under tons of links supporting my position until they beg for mercy.
I feel that DSB's are a viable solution that requires waaaayyyy more maintenance than I even want to contemplate in order to survive. If it doesnt survive, your tank will in all likelyhood crash.
Why??? Think about it. DSB's require lots of sand sifting animals to prevent pockets of hydrogen sulfide gas from forming, and to keep the sand turned over. They also require lower flow rates throughout the tank in order to prevent a sandstorm, so detritus isnt kept in suspension very well. Detritus not kept in suspension will sink. Detritus that sinks and isnt removed thru consumption, rots and fouls the water. Detritus that is consumed but cannot be processed by the consuming organism, is excreted, again...and will eventually rot, and foul the water ....this is, as we all know, a bad thing. Sand is very difficult to siphon clean, its relatively light weight allows it to be carried away w/ the very detritus we are attempting to remove. this doesnt exactly encourage reef keepers to clean the sand bed of detritus.
Backing up a bit, detritus can be considered as the end products of an organisms metabolism which may or may not contain substances we don't want in the tank. A good example of this would be fish feces. Lets say we have MojoReef's amazingly beautiful Vlamingi Tang. This fish eats a lot, (just ask him he'll tell you it does!) Since the fish is an herbivore most of its waste will be unuseable (to it) vegatable matter. This vegatable matter will most likely have loads of phosphates (found in plants) and loads of Nitrates, (also found in plants). Now the fact that this waste from the tang is primarily vegatable in composition will allow more omniverous scavengers to have a go at it as well, (hermits). But what they don't eat will eventually breakdown and release its remaining nutrients back into the tank...meaning the phosphates and nitrates jump up again....this causes nuisance algae blooms in this particular example.One way this could have been avoided is if the water flow was such that the detritus from the tang, (feces) was kept in suspension until it could be mechanically removed from the water column by filter pads or sponges or micron socks. Not having a DSB or any substrate at all for that matter allows for easy removal of detritus thru siphoning, and increased water flow w/o fear of substrate being blown around and irritating corals. Its getting late for me and I have school in the morning, so I will just basically sum up with...
This is what I'm going w/ for the bottom of my upcoming 58 gallon. Its easy to clean, and doesnt look bad at all. I can remove any detritus that I can reach w/ a siphon w/o fear of disturbing the tanks stability or my sanity.
Thats my story and I'm sticking to it!
Nick

 

[Maxx]

Rob Toonen has a tank that is going strong after 16 years.

Had...he admitted it was broken down a few years ago and parted out to a friend. The tank did not however crash, and was showing no signs of ill health at the time.
Nick

 

[reefshadow]

Hmmm, interesting discussion.

Chuck fiterman (mntdewman) had a similar crash which he has blamed on his dsb. And he had a beautiful and well thought out system. Yet one coral after another succumbed in a kind of chain reaction. Makes me kind of nervous, considering that dsb usage is really kind of in its infancy so to speak. I wonder how many long-term successfull tanks there are which have employed the "undisturbed" dsb method. (long term as in 10+ years).

Recent posts of that nature have made me wonder if that is something I really want in my display tank. I've contemplated removing mine and using my refugium as the main dsb. It would be easy to maintain, replace, and remove that way. Removal from the display will be such a hassle though!

It's so hard to say what can cause a downward spiral of a captive environment though, and a definative answer would require long term study and experimentation which no one is really doing.

The husbandry of captive reefs is definately becoming more easy, but only time can tell. This is still a very young hobby and involves so many aspects that it is hard to say what can cause a seemingly successfull reef to crash. Alot of experienced reefkeepers are now advocating the removal and replacement of both aged sand AND live rock. I'm not sure what to think about that, especially the removal of the rock. After all, it is very expensive and really isn't such a huge renewable resource that I would feel comfy chucking it in the can.

Are we entering the age of remote, maintained dsbs? I think maybe. I'm not sure what maintenance means though. Should we syphon and replace sections frequently? Add deitrivore kits regularily? That sound like alot of work and $ for little gain.

It sounds easier to just step up the water changes and quit worrying about a failing dsb.

I'm interested to hear your take on it, Tank Girl. How is your water quality doing as far as nitrates and phosphates? I know it looks beautiful!

And hey, if I remove my dsb I have more room for corals, eh? Hmmmmm. I'm thinkin about it!

- Becca

 

[reefshadow]

Maxx, I just read that link, and I really like it too!

I don't have a sb in my 125 prop tank and a rock fall would be scary. That type of material would be just the thing.

Looks kinda unnatural I think but I don't think it would look unnatural for long, that type of material would probably be covered w/ coralline in no time at all. (and zos, and shrooms etc.. etc...) and personally I think my dsb looks ugly under the surface along the front of the tank.

Someone also metioned using modified ugf plates. Maybe there is a use for them afterall?

Where can you get that starboard and what do you need to cut it with???

Cool link.

 

[wooddood]

i have a 120 with a 5in dsb and personally when i move my tank, very soon i will be going bare bottom from now on.this is a very good question travis.i will follow to hear others responces. thanks dave.

 

[Maxx]

Becca,
All throughout the Starboard thread people make reference to using table saws w/ plastic cutting blades. So I have not doubt you could get it done...somewhere....
As far as where to get from....Here is probably where I will be going. Usplastic.com also has cutting boards, but not in different colors. And I think I like the black best...will match the black back of the tank better.
HTH
Nick

 

[ScottT1980]

Just thinking through the science, would a plenum have all the same problems as a DSB? Its early and my brain is a bit slow at the moment...

 

[FishyinKY]

I don't think the blame is on the dsb. I think more the blame lies on the natural die off of creatures in the DSB. I think that they have a life cycle and unless you provide them what they need to continue to grow and multiple or have something that lives and lasts a long time. For instance there are places in my dsb that are up to 6 inches high. My gobies move the sand as do my spoon worm, bristleworms, queen conchs, and even one of my damsels. I know that my tank gets depleted from creatures like pods but having the refugium seems to keep the tank continuously supplied in new ones and I can always reseed if it looks like the bubbles in the sand are not enough. I was thinking about what you said about detrious. I have lots of tangs and they eat lots of greens. But my two spot gobies love what they poop, as do the serpent star and brittle stars. The thing that occurs in my mind is that the ocean is constantly changing and renewing yet in our tanks we don't do the same. We get the tank exactly as we want it and then we don't touch it. Except to do maintaince? Perhaps its the very stagnation that causes the tank to have the problems?
Now I'm throwing ideas out here for discussion. Maybe we need to add new sand or take bits out or perhaps we need to add creatures periodically. Perhaps to keep our deep sand bed healthy we need to find some way to feed it or to pick particular creatures to address what we have in the tank. What do you guys thing?

Mac

 

[Scooterman]

Ok I stayed with the thread from the beginning, I know most of you may have seen it but If it is ok I'll post the link. Remember this thread has almost 5,000 post, so reading will take some time, It covers Jerels, Starboard & the mighty 16yr old tank. It took about 6 or 8 months to cover this thread from the very beginning.



http://www.thereeftank.com/forums/showthread.php?s=&threadid=23293

 

[ScottT1980]

FWIW, having a flatworm problem is great for a DSB. I siphon the top layer of my SB almost weekly with a hundred or so flatworms.

 

[mojoreef]

Oh man.... here we go again. The BIGGEST problem about DSB's is that folks just dont know how they work. Just reading the posts you can see it. Also alot of folks lame DSb's for crashes and even have tried to tie them to old tank syndrome, which are both not the case.
Ok if we are going to have a discussion we first need to understand how a DSB works. Then we can understand what makes it viable and what doesnt.
Here is how it works. A DSB is an enviroment that skews itself to the creation of bacteria. The fine grade particle as most folks know allow more surface area and thus more of a population. In the bed thier are a ton of different types of bacteria that need different enviroment in order to live, they also require different food sources. Also a big miconception is that baceria export, well they do and they dont so here is how it works.
In the areobic zone (the top layer of your sand that is saturated with oxygenated water) In this layer you have all the critters that everyone talks about (pods/worms/nematopes/ larvae and so on). The critter tht live in this zone will eat detritus and waste, but they also poop out more then 90% out in back in, plus they also die, so thier is no real export to get from them. The real work is done by baceria. The bacteria that works this zone reduce detritus and waste. They do this by stealing protons and electrons. an example would be NO3 to NO2 and down. The problem with them is that they only reduce nitrogen based products. Every thing beyond nitrogen based is not consumed and not reduced, so with the stirring action of bacteria and critter these non nitrogenious product slip down into the bed along with the biporduct of this first wave of bacteria (nitrates).
Now you begin to enter the first stage of anaerobic. This is a zone where the oxygen begins to deplete. The first layer of bacteria in this zone are the types that will begin the process of denitrification. These bacteria can comsume oxygen, but when it runs out they turn over and fix nitrate instead. Now once again through the action of bacteria and critters this are is seeing a constant flow of detritus. The detritus consists over nitrates from the actions above (nitrogen based products ) and alll the other things we put in our tanks that are not nitrogen based (some of these would be phosphates, sulfides, metals, bacterial flock, enzynes and microbes used by bacteria to reduce). SO in this upper part of this zone the bacteria will again reduced (stealing protons and electrons) nitrate through a pfew stages until it leaves and end product of dinitrogen gas. Now once again through the action of bacteria and a few types of critter this gas is allowed to escape up and usually off gasses out of the tank. Because the nitrogen cycle turns its end product into gas and critter action releases it this is a form of export. So we can all agree that a DSB is a very productive denitrifier..and it is. IF you have the required critters stirring. This is the good part of a DSB.
Now it doesnt stop here. Non nitrogen based waste, bacterial flow (mainly thier shells and dead bodies) enzynes and microbes( things used by bacteria to reduce as they need to liquify thier food to eat it, phosphates, sulphides, particle dust (small sand particles reduced to dust through movement and reduction) Hydrogen and organic acids and so on still move down. OK the next round of bacteria that dominate are the sulfate reducers. They again reduce the same way as the nitrogen bacteria but thier final end product is sulfide gas. Not a very friendly little thing. BUT again now all the stuff that is not nitrogen based and not sulfate based continues to move down along with all the stuff that was used in the above process. Ok now if you have a deep bed say 6 inches you get into the methagen reducers. and then the metal reduces. anyway the rest is boring and doesnt come into play unless you dig inot it.
So the food that is once placed into the bed through feeding and waste and additives has gone through and been cycled (bacteria reducing) and you are left with a variety of end product (from argonite dust, to enzynes to dead bacteria to all the other products put in that do not get reduced) this is what builds up in a bed, the building up of these products will raise the anaerobic zone and reduce the areobic zone as time goes by. Which will eventually saturate the bed and render it useless.
So thier is the biological concept behind a DSB filter. This is exactly what it does and it does these things well.
So now with this understanding we can talk more about if its problems, its goods, how to save it how to kill it or how to work with in its boundries.

Travis youre a S*** disturber, lol

Mike

 

[tankgirl]

A great post by tdwyatt that I wanted to share;

DSBs DO process Carbon, the DO break it down to its final mineral ash, bacteria do play their role in doing the nitrates and they DO sink a goodly amount of the stuff we don't want in the water column. Heavy feeding will always load the water column with nitrogen, phosphates, DOM as fats, carbohydrates and proteins, and minute particulate materials (forgive me, but for the sake of discussion, reef AQUARIUM snow and I don't mean 2 little fishes product ).

We want these things that get the most of these organics to be larger organisms: macroalgae, microalgae (in the case of those that are fed on by snails), sea cukes and misc. nematodes, polycheates, etc. that are either capable of being consumed by higher organisms and turned into biomass, or are harvestable and exportable, which is what making the DSB work is all about : making the stuff we don't want exportable.

There are a large number of heavy metals that chemically bind or are in ionic association with carbonate sediments. All the divalent ions are capable of binding in the place of calcium to the carbonate in the sand bed, some form insoluble bonds, some are in equilibrium with soluble phases of the ionic forms. Phosphate is a good example: It forms a highly insoluble salt with calcium and precipitates out of solution, especially with Kalk additions, effectively removing phosphate as a source for nuisance algal blooms. The sandbed has no export or processing capacity for phosphate, so this substance builds over time, leading to potential mass release during substrate disturbances (like stirring the substrate). The only way of preventing a buildup of phosphate is to find some way of exporting it, either (can't believe I'm saying this) use an algal scrubber and harvest the microalgae, or use a refugium (my preference) and export the macroalgae.

DSB's do work, They work well when constructed correctly, established over time, and tended carefully. The trick is still in the details of out husbandry skills. We will need to watch them as we would a bathtub with a leaky faucet dripping into it, and we can't remove the plug. Much like this tub analogy, we can control how much stuff goes in, and we can bail water out over time to prevent it from overflowing (even to the point where we could take out some of the sand), but that is where we stand at this time. The sandbeds have limits, and although we can make them work and work well, there will come a time where they will need drastic measures to keep their functionality.
------------------
Also;
One of the worrisome things I've read;
Dr Rob is now saying DSBs work, but require regular replenishment of detrivores. But, he's also saying most commercial detrivore kits don't have sufficient variety in them for our needs.

Additionally, Dr Ron is saying that remote DSBs can't work.

 

[tankgirl]

Another comment by tdwyatt that's worrisome;
"If you want remote sand beds that work appropriately, you need water current slow enough to allow regenerative sediment settling."
-----
DSB's work fantastic on lagoonal soft coral type tanks. But the increasing realization that sps corals require high levels of water movement to thrive, is changing the way we run our tanks, and higher water movement levels present a problem for DSBs
-----
Also; a great post by adam

Any and all materials that aren't gassed off or aerosolized (trivial amounts except for carbon and nitrogen, and maybe a bit of sulfur) get incorporated into substrate, organics and organisms. These things must be exported. Period. for the rest of this post, I am referring to these materials

Nutrient cycling is important, but it is just that.... by definition, if it is cycled it doesn't ever leave. Choose your method... Skimming, Turf scrubbers, water changes, macro algae, whatever, but get rid of it. read on....

Populations of organisms in a DSB will rise and fall with available nutrients, but have upper population limits determined by factors other than food (space, primarily). They cannot infinitely absorbe this stuff and keep it incorporated. As they die for whatever reason, are replaced, and their nutrients are processed, where do they go? They go to DOM's, some get incorporated into sediments (a good bet since that is where they are!), etc.

Wherever they end up, they have to be removed. In a tank without a DSB, that means vacuuming, skimming, refugia and/or water changes in some combination. In the case of a DSB, that probably means periodic partial substrate change (probably in addition to skimming, refugia, etc).

I believe strongly that one of the reasons that DSB's are so successful for short periods of time and then rapidly decline is that they are very efficient at processing waste while the organisms in them are still growing in population toward their practical limit. When that limit is reached, and the popluation stabilizes, nutrient assimilation drops dramatically.

IMO, harvesting/exporting of animal mass is highly underrated as an export mechanism. Frequent trapping and harvesting of animals capable of rapid repopulation is a fantastic export mechanism. Bristle worms, several types of herbivorous snails and many sand bed critters are easy to harvest. Periodically removing and replacing part of a DSB will harvest a significant biomass as well as keep the infauna population constantly growing keeping nutrient assimilation high. It will also export any wastes incorporated into the sediments themselves.
----------------
Another of the problems (as I understand it) is that with fluctuating nutrient levels, bacteria flourish and die. When they die, they release all the stuff locked up in their biomass - to fuel an algae explosion. Then as algae dies off, it refuels a new bacterial population increase - and so on in a vicious cycle.

 

[mick77]

Head hurts, too much information at once, need coffee. JK Excellent info mojoreef, for an instant I was transported back to Biology class (man I wished I would've let it all sink in more). I'll keep this thread marked to see what all everyone has to say about the controversial DSB. Am I missing something, but don't the tides constantly turn over the sand bed in the ocean? If this works in nature, why couldn't we simply stir our sand on a weekly basis in our own tanks?

 

[Scooterman]

And I thought My head hurts LOL

 

[angnak]

Just tagging along.

 

[Imperial]

uhhh wow that's alot of info. :columbo:

 

[mojoreef]

LOL TG TdWyatt is a very good friend and a very smart guy, and has alot of points that do need to be addressed, I have doen it for him befor but for sake of education like do it again.

DSBs DO process Carbon, the DO break it down to its final mineral ash, bacteria do play their role in doing the nitrates and they DO sink a goodly amount of the stuff we don't want in the water column. Heavy feeding will always load the water column with nitrogen, phosphates, DOM as fats, carbohydrates and proteins, and minute particulate materials

Toms overall concept of a DSB is to allow it to be the sink that it is, then simply remove it when it fills. Now this is a viable options for folks that want to do it this way. But I believe if most folks had that knowledge about it they wouldnt pursue it. The carbon Tom refers to is what is use for respiration, as in the energy the critters use in thier daily lives, but it is very insignificant when looking at the whole picture. Bacteria, ligants, chelators will bind metal and other toxins, but they will do that as soon as the hit the water column if they are free ions or loosly bound ions, so it doesnt pertain to the critters in the bed. Although the critters in the bed will also do that but they will physicaly remove it from the sand particles themselves.

There are a large number of heavy metals that chemically bind or are in ionic association with carbonate sediments. All the divalent ions are capable of binding in the place of calcium to the carbonate in the sand bed, some form insoluble bonds, some are in equilibrium with soluble phases of the ionic forms. Phosphate is a good example: It forms a highly insoluble salt with calcium and precipitates out of solution, especially with Kalk additions, effectively removing phosphate as a source for nuisance algal blooms. The sandbed has no export or processing capacity for phosphate, so this substance builds over time, leading to potential mass release during substrate disturbances (like stirring the substrate). The only way of preventing a buildup of phosphate is to find some way of exporting it, either (can't believe I'm saying this) use an algal scrubber and harvest the microalgae, or use a refugium (my preference) and export the macroalgae.

Tom is dead on in this, and this is more important to us as reefers then the build up. it is the conctant algae battles that will discourage us and make us finally give it up or quit. So this is the problem we really need to work on. Phosphates will create a cycle that is hard to break with in the bed. A refugium down the line will not touch what is happening here because the phosphates in the bed are not availble to them and/or locked up prior to getting to them. The cycle is simple, phosphates are added to the tank, lets say through feeding, food and waste hit the bed, bacteria b egin to reduce it algae begins to absorb it, you get a small algae bloom based on the ammount of food available. as food is used up the algae dies off and the bacteria population grows from feeding on the decaying alge, this now runs out and the bacteria die, they decompose and the alge has a new food source. just a simple cycle. You can harvest the cyano or hair and it will be exported but most folks dont like that. Now with continious feeding the cycle gets bigger as more and more food is available, you eventually hit a point of saturations and now your in constant battles. Thier are ways to beet it but we can get back into that later.

Mike