why are we running DSB and is it for the right reasons

[sumpfinfishe]

When I was in Germany a few years back, I visited some serious fish stores there and asked about this subject. The 6 or 7 people that I spoke with, all had DSB's setup for 10 years or more. I was told in order to keep things clean, some would siphon out 25% once a year and replace it after a good cleaning, others told me that they would simply stir it up and run a canister filter for a few days, and the rest told me to go with an inch or two and to use lots of critters like snails and crabs.

My DSB is about 4 years old now, as I replaced my entire SB after two years into reefing-don't ask I plan to keep my 2" DSB until I see reason to change. My only concern is that if we eliminate or reduce our DSB's aren't we not going to see these harmful elements transfer to our LR or worse to corals and fish

To make a final comment on this great thread, I am planning next year to clean 50% of my entire DSB. Sure this is going to be a major rip-out even in a 27gl, however I would rather spend an entire day cleaning my reef rather than loosing 6 years worth of hard work and beauty.
cheers, Rich

[StirCrazy]

Originally Posted by sumpfinfishe

To make a final comment on this great thread, I am planning next year to clean 50% of my entire DSB. Sure this is going to be a major rip-out even in a 27gl, however I would rather spend an entire day cleaning my reef rather than loosing 6 years worth of hard work and beauty.
cheers, Rich

See you are never letting your bed get old. by changing it you are getting rid of saturated sand and replacing it with new. what you are doing was originally described as a no no by Dr Ron as the original premise of the DSB was to never to disturb it.

It is the Germans that are being portrayed as not using DSB's anymore. (I haven't been able to get ahold of my cousin to get him to check into this for me) but from what you discribed they are not realy running a DSB in the true sense. they are manipulating it to drive it closer to a bacterial driven bed than a "critter" driven bed. So same name but two different animals.

Steve

[kari]

Steve;

What do you figure with the partitioned SB idea? Are you striving for nitrate reduction or other benifits of a SB like feeding or maintenance cutback solutions? My thoughts are getting off track.

[StirCrazy]

personaly I don't feel that feeding from a sand bed is a reality anymore as stated befor there have been saying that with the limited sand bed bio diversity in our tank the plankton produced is the wrong type or of a insufficient amount.

So my stand now on a sand bed is that it should be used and a nitrate reduction system and changed out at regular intervals. as to how long thoes intervals are I am not sure but I would guess between 2 and 4 years.

now seeing that it will be running for a significant amount of time it is inevitable that it will be popluated with creatures and intourn supply the rest of the system with some sort of life also.

as for partitioning if you are going to do it with one bed that would work fine, but you might want to set up 3 partitions and fill them all to start with. then each year pic one and replace it. this will give you a 3 year turn around eventualy on each partition which should work fine as most people who have had problems see them in the 4th and 5th year it seems.

Steve

[powerreef]

Its a tough debate. DSB's are very forgiving for the new tank and new user. They give the reefer an easy way of avoiding maintenance and not being punished.
I fall on the Nay sayers side, but I do see some advantages to a sand substraight. People who use DSB's use them for 2 basic reasons. One is for denitrification and the second is the bug life that it contains. These are 2 good reasons but a DSB is not needed to achieve them. I will elaborate a little more below. The inherant problem with DSB's is that they dont process everything. In reality they only process nitrogen based products, this would leave everything else unused and thus still in thier. Because our tanks have a bottom, this unused stuff piles up. As it fills (and nobody knows how long that takes, it has to do with feeding ammounts and husbandry) it drives the anerobic nd aerobic zones higher in the sand column, and because thier is a surface the upper zones just keep getting smaller and thus loose thier filtering compacity. Another huge problem and probibly the one most reefers encounter is the inability to deal with Phosphates. Concidering that all life in the bed carries phosphates and the simple PHosphate cycle of an argonate based sand Phosphates will leach back into the tank. This is where you see folks having problems with patches of algae here and cyano over thier and so on. An endless cycle of algae blooms.
Nitrification and 99% of all bug life lives in the upper aerobic zone. All bugs with the exception of bacteria/enzynes and protozoas need oxygen to live. So here is the way nitrification works in your bed.
dinitrogen is reduced by reduced dinitrogenase (which uses a coenzyme containing iron and molybdnym to carry out its reducing activity) to form dinitrogen dihydride (requires reduced dinitrogenase, 4 protons and 4 electrons)
dinitrogen dihydride is reduced by dinitrogenase to form dinitrogen tetrahydride (requires reduced dinitrogenase, 2 protons and 2 electrons)
dinitrogen tetrahydride is reduced by dinitrogenase to form 2 ammonia molecules (requires reduced dinitrogenase, 2 protons and 2 electrons). Sounds complicated by its a pretty simple process with nitrate as the end product. From here nitrates are brought down to the anerobic zone (a thi layer of both mixed oxygenated and anoxic zone. Now bacteria once again reduces nitrates to nitrogen gas. The bacteria that do this are facultative (means they consume oxygen first and when it runs out they go after nitrate ..basically). So once it is converted to gas the movement of bacteria and critters allows the nitrogen to off gas (the little bubbles you see in the bed).
From this point thier is nothing in your bed that does anything for your reef tank. These 2 zones can be fully operational with only a 1 1/2 to 2 inches of substraight, using either oothilic or even CC.
Now on the down side of this in the deeper zones we have a suphur cycle, iron cycle and a varity of nasty operations done by infuana that will never benefit the tank in itself. So why have it????? Thats why if one feels the need for sand in a tank 1 1/2 to 2 inches is more then enough to do everything you want. When the build up of things that are not nitrogen based occurs one can simply syphon out the entire sand bed, and thus rid yourself of any long term problems. People argue that it will kill your nitrate reducing bactering, this is simply not true, they are facultative and will simply consume oxygen until once more it runs out in the bed (very quickly) then they will revert to nitrate once again.
On the remote DSB, been thier done that. Bottom line is that it is not needed. A shallow bed will do everything you want, with out having to do the big nasty down the road. Also if you choose to set up a remote make sure you have a real long ammount of contact time, or it will turn into a settling tank in a hurry. IMHO a remote refugium with a 2 inch bed of sea floor and macro's are more then enough to take care of any dentrification you will ever need. Lets not forget the L:R that does the same thing .

Anyway sorry for the rambling

MIke

[StirCrazy]

Hey Mike, I was under the impression from Randy, Bomber and my own experence with fresh water tanks and DSB's that it was the bottom level (the anoxic zone) that actualy did the final nitrate to nitrogen gass conversion.

I have been running a DSB in my fresh water tank for 3 years now but I also have a ton of plants in there which help take the nasties out of the sand bed, could we set up a salt water plant remote bed that would work the same way?

I don't want to use macro algae or algae period, as it alwasy finds its way into the main tank but maby some grasses or other rooted plant would work.

Steve

[ryan_p]

I was sure that I was going to go with a DSB but know I am faced with a good arguement for both and really don't know what I should go with. I have the advantage of knowing that I will be having to tear the system down in 2 - 3 years once I finish school and relocate (victoria, probably). So if i do encounter a reason to change/clean the sand bed it can be done at this time. As someone said earlier, dsb's are more forgiving for the new reefkeepers. So I still lean toward going with it, but with some apprehensions. If you were going to be setting up a tank (46G) knowing that it was going to be moved in a couple years, what would you do for a sea floor? I like the idea that Kari had about seperated chambers for dsb's in a sump/fuge, but I probably won't setup a sump for a few months.

[powerreef]

Stircrasy this is they way it works. The bacteria that consume nitrate also consume oxygen. They will only consume nitrates once the oxygen is depleted, so for that you could say it need to be anoxic, BUT, they aer also the first in line and inhabit the zone that lies between aerobic and anoxic. A zone we call anerobic. So as this relates to the DSB thingy we have a 1 to 1 1/2 of sand for the aerobic and then 1/2 inch for the anerobic then 4 inches of anoxic dead zone. So to answer your question nope the nitrogen off gassing does not occur at the bottom of the anoxic zone, it occurs in the anerobic zone.

I have been running a DSB in my fresh water tank for 3 years now but I also have a ton of plants in there which help take the nasties out of the sand bed, could we set up a salt water plant remote bed that would work the same way?

Well most folks call that a refugium and it does do a pretty good job at nutrient removal. However algae cells are very leaky and for every percentage they absorb they leak out a good quantity right back in to the water again. Seagrasses are alot less leaking but also have some light reuqiring needs, but If I was given a choice it would be the grass for sure.

Ryan it all boils down to maintence. If you simply remove the detritus from your tank with a simple Syphoning you dont have to deal with it. Poof its gone, nada, no cycles no problems just gone.


Mike

[StirCrazy]

Originally Posted by powerreef

However algae cells are very leaky and for every percentage they absorb they leak out a good quantity right back in to the water again. Seagrasses are alot less leaking but also have some light reuqiring needs, but If I was given a choice it would be the grass for sure.

Mike

exactly that why I want to do it with grasses instead of algae. also with grasses you get the root system that will help clean the junk out of the sand extending the life of the bed.

I have a refuge right now but it is got bug growth only, so it 2" of fine sand, 2" of coarser sand on top of that and a bunch of rubble. I do not light this one at all. but I would not have a problem with making another one with a few floressent grow bulbs over it to light up some fast growing grasses.

Steve