DSB...Let's Discuss!

[NaH2O]

Mike, my understanding (correct me if i'm wrong...which i'm sure i am), of sand replacement, is to keep some of the sand from clumping and holding onto the undesirables, such as phosphates. In my mind, it is similar to pruning macro algae...nutrient export. Get rid of it before it eventually leaches back into the system. Every so often introducing a small amount of fresh live sand with a detrivore kit of some kind...will keep the sand bed from exploding, like Rogue's picture....

[Scooterman]

Thanks for the information everyone, so Mike Is picking into what will become a good discussion I hope

[mojoreef]

Mike, my understanding (correct me if i'm wrong...which i'm sure i am), of sand replacement, is to keep some of the sand from clumping and holding onto the undesirables, such as phosphates. In my mind, it is similar to pruning macro algae...nutrient export

Ahhh Ok I got it. Hmmm... I wouldnt bother if it were me, The sand is phosphate saturated before it even comes out of the bag. so it wont do much to replace it. The clumping is cause by hard water (which we want) with the lack of stiring, in the case of DSB's by bugs I guess. The phosphates bound in the sand will not leach back into the tank unless a couple of things happen. One is if they are dropped inot a lower zone of the bed in which the ph is low (whih is what is ahppening already in the lower depths of the bed) and or it is melted by bacteria trying to access the food source (which is already going on anyway). So thier is no real method for beating this part of the equation, basically you must live with it. The other way that phosphates enters the bed is through food/waste/detritus, this stuff is what loads into the pore water of the sand bed, this is the only stuff you really have a chance at exporting, but again the only way is to physically remove it, which tends to go against most DSB mantra..


Mike

[NaH2O]

OK...so let me see if I have this right....there is no way of preventing the phosphates from getting into the sand bed, because it is already present in the sand, and essentially it will leach....because if it's in the sand then it is going to be in the lower zone. However, I can control the top portion by syphoning the upper layers, say during water changes, and having good water movement trying to keep the detritus in the water column. What about trying to keep the critters in the sand bed fed in order for their job to be done. If I keep removing their food source, then I potentially won't have critters. What changes can I do to the system to make it work? Maco algaes in the fuge to absorb the phosphates, etc.?

[Scooterman]

You won't remove it all & whatever you have left over the critters will populate according to what is available. Ok so what you have less critters that the rest, your bed will have a better chance of living longer right?

[NaH2O]

With less critters, would the sand bed be fully functioning? I guess there would be enough life to keep things moving in it *(thinking out loud)*. Scott, I'm following what you are saying, I'm just trying to get a handle on this so I get the most out of my system by understanding it.

[Cougra]

Originally posted by NaH2O
Michelle, do you have any ideas on what was causing the tank crash?...maybe the CC?

That was part of the reason! I didn't know much about setting up tanks when I first set this one up. I think I basically had way too much detritus build-up under all the CC despite attempting to keep it clean. It reached a point where the system couldn’t handle the load anymore and started to through off my water chemistry.

When problems first started in the form a small cyano outbreak, I figured that my lighting needed to be changed; when that didn’t work I tried reducing photoperiods and increasing water circulation, followed by reduced feedings and frequent water changes. I removed some of the bioload and put them into separate small tanks and added some more caulerpa and thing continued to get worse instead of better. Hair algae slowly took over my tank and despite all this extra growth in algae/cyano I STILL had nitrate readings in the tank. I knew I needed to do something drastic and changing the substrate was the next course of action.

I read about a lot of people having problems with their tanks crashing and faced the reality my tank could be considered one of them.

Originally posted by mojoreef
I was wondering why the replacement of sand?? I am not sure I follow this.

Mike

Mike:

My primary reason for changing out a bit of sand constantly stems from what I’ve seen with my previous substrate. The tendency of detritus to fall to the bottom and eventually pollutes the system. I’ve tore down a few tanks in the past and have always found that the bottom of the tank had the same disgusting sludge that reeks to high heaven! (Similar to what we were talking about in the plenum discussion.) I want to remove as much of that detritus as possible to help prolong the life of the sandbed.

I can’t really figure out a way to get rid of this sludge at the bottom of the tank without removing the sand as well. Thus I found the concept of having a plumbed system under the plenum a very interesting concept and could see some potential for it.

Originally posted by mojoreef
The clumping is cause by hard water (which we want) with the lack of stiring, in the case of DSB's by bugs I guess.

I realise that the critters in the sand are suppose to do this for you and if you have an adequate number then this shouldn’t be a problem. However I feel there is still a possibility that the creatures aren’t going to do a good enough job due to low population or some other unknown factors. I guess I could go poking around in the substrate to find out if there are some problems with clumping and take measures in needs be.

Of course I’m open to suggestions on how to prolong the life of the substrate and being told that my ideas so far are completely off base!

[Scooterman]

It you dump more food then it will have to repopulate to accommodate, & thus will turn over you bed quicker but at a price, more creatures leads to more processed waste & eventually they will reach Maximum for your bed size then some will die off leading to more waste, these critters poops also at some level, which more smaller critters eats but same for them also, eventually whatever gets processed by all the critters will clump up, it doesn't vanish & if you take an aluminum can and smash it and smash more until it is very small, is the total mass any less? How can all the food just disappear, where does it go?

[NaH2O]

Originally posted by Scooterman
How can all the food just disappear, where does it go?

A good magician never reveals his secrets...

[Cougra]

Originally posted by NaH2O
With less critters, would the sand bed be fully functioning? I guess there would be enough life to keep things moving in it *(thinking out loud)*. Scott, I'm following what you are saying, I'm just trying to get a handle on this so I get the most out of my system by understanding it.

When I say remove sand I mean I’m going to change out a smaller portion of the bed, maybe and 1/8 of the substrate at a time. Yes this is going to hinder part of the sandbed until it can get repopulated, yes this is going to reduce the critter population however it’s also going to make room for the remaining critters to multiply in, this added with a new influx of bio-diversity from new live rock, trading sand from another tank or purchasing more critters, will help keep the critter population healthy.

[Scooterman]

[mojoreef]

OK...so let me see if I have this right....there is no way of preventing the phosphates from getting into the sand bed, because it is already present in the sand, and essentially it will leach....because if it's in the sand then it is going to be in the lower zone.

You cant control the phosphates that are in the sand, unless you dont put it in. You can control an ammount of the phosphates entering the bed by not allowing the phosphates that are associated with detritus/food/waste and so on to enter it but kinda defeats the purpose. The concept now being purposed by the PHd's is to allow the cyano/algae portion of the phosphate cycle to occur and then to syphon the cyano and so on out, this way you are breaking the cycle and actually exporting something.

However, I can control the top portion by syphoning the upper layers, say during water changes

you could but you have to becareful. two things to look out for. One is watch for the sulfide zone (grey sand) hit that and you could have problems. The second is you have to look at the whole bed. You are going to have the ananerobic zone raiseing in the bed (along with all the products that a DSB doesnt process), now at the same time you are shaving off the top....at some point in time your going to meet, hehehe

and having good water movement trying to keep the detritus in the water column

yep thats what folks do that dont have DSB's, this way it keeps the detritus as a food source for those that feed on it, or it lands in the bed and feeds it instead.

What about trying to keep the critters in the sand bed fed in order for their job to be done. If I keep removing their food source, then I potentially won't have critters.

The larger critters in a dsb (pods/worms and such) are thier for what is called bioturbation. Thier movement allows for the migration of elements through the bed. They are not really thier for thier reduction capabilities. They will find food dont worry, lol

What changes can I do to the system to make it work

Boy thats a question that even the big boys cant answer. Hun the DSB is what it is. A DSB is set up to be a recycling center not an export devicd (with the possible exception of nitrogen) .

Macro algaes in the fuge to absorb the phosphates

You can do that for sure, it will allow for the absorbtion of nutrients (both P and N) that are in the water cloumn and happen to come with in grasp of them. As per this helping a DSB, no chance. the phosphates bound with in the dsb system that are leached will be taken up on the spot by algae and will not be available to the marco that is somewhere else. This is why cyano is so previlant with dsb's, Cyano is a super absorber when compared to macros.

Mike

[NaH2O]

Thanks, Hun...I mean Mike ....I guess when I asked what can I do to make it work I meant what can I do to help it work.

One is watch for the sulfide zone (grey sand) hit that and you could have problems. The second is you have to look at the whole bed. You are going to have the ananerobic zone raiseing in the bed (along with all the products that a DSB doesnt process), now at the same time you are shaving off the top....at some point in time your going to meet, hehehe

I see what you are saying about the zones meeting eventually. What about introducing some live sand every so often...little by little in order to keep the zones separated?

When I say remove sand I mean I’m going to change out a smaller portion of the bed, maybe and 1/8 of the substrate at a time.

Michelle, I had planned on this as well. I wonder though if there is a build up of hydrogen sulfide (is that right?) when the sand is removed in the display...however much....would we run the risk of exposing our inhabitants? I also plan on having DSB in my fuge, which I will be able to take off-line and change out the substrate as maintenance.

Another point I guess should be made, is what depth of sand is considered DSB? I've planned a sand bed in my main system of ~4 inches at the highest point.

O.K. Mike, teach away......

[mojoreef]

Sorry about the hun thing, lol ..bad habit.
See Nikki this was the whole reason I started the plenum thread. The concept was to let everyone know how things work biologically, that way it gives you a better chance on manipulating it or know if what ever system can even work. Ok lets get to biz of breaking down a DSB.LOL
When looking at a system like this we have to look at limiting factors. knowing these can help us fool around.
When worrying about a bed going anaerobic, we can look at these limiting factors. the presence of oxygenated water will not allow it to go anaerobic, so we know then that we have to do that. Now because the grain size is so fine its harder (you can kinda see where I was going with particle size in the plenum) but not impossible. large stiring critters like cukes, or big stars stuff like that. Or a million worms and a billion pods. you could introduce more sand no problem, but I dont think it would make a big enough impact and as time goes by you wold have a sand tank, lol.
Even knowing the problems with a DSB I did one for 2 1/2 years, figuring I could out smart it and manipulate it to where I could make it work. Manualy stirring the bed and syphoning out the detritus that came out of it worked for me in keeping that upper level aerobic. With the rocks on top of part of the sand I couldnt do anything their but hope the bugs could manipulate. I spent hundreds of dollars of detrovoir kits and so on. The sand under the rock was anaerobic and had a sulphide zone 1/4 inch down. In the display I was able to keep the anaerobic zone down about an inch. Sulphide zone down about 1 1/2inches. I battled the phosphates (and believe me I know a few tricks) but couldnt win, the battle became more and more of a loss (as in cyano/algae blooms) were coming back more often and quicker. Their is no way a DSB cn deal with phosphates, you only chance is to make sure you limit the ammount you put in.
Can I ask you a question, why is it that you want one??

MIke

[RogueCorps]

Hey Mike,

Do you have a link to the case studies you've read or could you send me those?

Thanks!

-Rogue