DSB in a bucket for nitrate control

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I honestly don't know how long....I've been told a month or two (mine has been in for just 2 weeks).

From what I've read the sand grain size does play into the capacity of a sandbed as smaller grains will give you a much larger surface area for the bacteria to grow on....which is why finer grained sands are recommended for use in DSBs..

From this article by Dr. Shimek...
http://www.erdingtonaquatics.com/sandfiltration.html

In a given volume of sand, the usable bacterial surface area rises rapidly as the average particle size decreases. For example, a cubical particle 1 mm on a side has 6 square mm of surface area, while the surface area on a particle that is one eighth (or 0.125) mm on a side is a total of 0.09375 square mm. However, in the volume of 1 cubic mm, there would be 512 of the smaller particles, for a total area of 48 square mm, eight times what is found on the larger cube. The total sediment surface area in even a small tank is impressive, indeed. In my 45 gallon reef tank, the sand bed averages about 4 inches deep, by 12 inches wide, by 36 inches long, for a total of one cubic ft of sediment. I won't bore you with the calculations, but if the average particle size is one eighth mm, and that is a good average size to have, the total sand surface area is about 14,828 square feet or just slightly over 1/3 of an acre. A LOT of bacteria can live with that amount of space!
Click to expand...

I have no idea as to the capacity of a DSB for a given volume or total surface area-- I suppose it is possible you have reached a limit or it just hasn't been fully populated yet....
 
What are tell tale signs that the DSB has become fully populated with bacteria, other then the nitrates dropping? I've heard that one can see nitrogen bubbles rising to the surface inside the 'glass tank' and on the surface of the sand. Is this true?
Thanks,
Jeff
 
Can population speed increase if you seed the sand? Maybe bottom, middle, and top with a thin layer of LS. This will put a *lot* of bacteria where it needs to be. I realize some bacteria is in the water column but why not just put some in there to help the process? I don't know if it would help, but I really would doubt that it would hurt none-the-less.
 
What happens when you have an over or under capacity of your RDSB for your tank?

For instance, a 10,000 gal tank full of sharks, ect, and supporting it with a 5gal bucket of sand. Does the bucket just run at capacity and the rest of the nutrients just build up in the water with no impact on the dsb?

OR... what if I have a 10 gallon nano with a six line wrasse supported by a 5gal bucket RDSB. Will the bucket never reach it's theoritical capacity of bacteria? Is there a negative impact?
 
Good question mmmsushi. I was wondering the same thing, maybe an expert will comment on this. I'm sure it depends on more things than water capacity.
I would think that these would all contribute to how much sand is needed:

water volume
bioload
current filtration (be it mechanical or biological)
consumption/breakdown (along with filtration if you have all steps in the cycle)
input (food, nutrtients, etc)
output (water changes, skimming, etc)
 
Bacterial populations are highly dynamic. If you increase the demands on a tank, their populations will expand logarithmically until there is no more need for the populations to increase.

In other words, a low demand on a RDSB will create a bacterial population that is fairly equalized with the bioload. Add another fish and the population will grow. There would be no negative impact from having an oversized bucket.

GREAT POST ESHOOK!!! :thumbsup:
 
I understand everyones thoughts on this. However..inwall75...If my nitrates are still around 30 with weekly water changes of 10%, I am still curious if there are tell tale signs of what we should be looking for by looking at the DSB tank...to see if it is percolating properly. Gas exchange?
 
If you are running a RDSB and still are maintaining 30ppm on nitrate, I suspect there is an issue somewhere in your system.

Do you regularly turkey baste your LR? Do you have any kind of mechanical filtration anywhere that needs to be cleaned? (i.e. filter sock, filter floss, canister filter, etc.) Additionally, do you overfeed or have too high of a bioload? I'm wondering if there is enough rot going on elsewhere for your bucket to keep up.

As far as gas exchange is concerned, I would say that if the water is rippling as it goes over the sand, you should have pretty good gas exchange.
 
I don't have any tidbits for you ReefLurker, on the "tell-tale" signs, but it might help if we knew something about your bio-load, display tank substrate, feeding habits, and how often your filter sock is "cleaned-changed".

The DSB does not take a different amount of time, regardless of depth. Let's use 4" as "minimum" depth for DSB. Deeper beds last longer, but the denitrification is occuring predominantly, between 1/2" and 4" deep. SSB's ( usually 2" or less ) do not denitrify "significantly".


> Barry :)
 
The reason I hooked up a DSB is that my 120 & 125 only has an inch or so of Coarse aragonite in them. Only to enhance the bottom of the tanks. There is about 125#'s of LR in the 120 and around 75#'s in the 125. The only filtration I use is a filter sock which is changed twice a week, after I turkey baste the rocks in the two tanks. I moderately feed the 120 reef tank twice a day and the agrressive 125 once a day. I dont think the bioload between the two tanks is substantial.

I feel the two display tanks are relatively clean inside them. The 120 reef has a Hammerhead pump for the closed loop and the 125 AGA has (2) Mag 12's providing circulation.

Since I incorporated the DSB in the system, my nitrates havent lowered at all. Thats why I am curious as to how long it takes for a DSB to 'fire up". I thought I had read somewhere where one should be able to see nitrogen gas bubbles forming inside the glass of the 30 gallon DSB or on top of the sand in the DSB.


Jeff
 
Wow I just read the whole 20 pages:eek1:
I would love to try rdsb but my question is if I set one up using a MJ1200 would bucket overflow enough to return back to the tank (about 5ft high) as I have no sump:mad2: I would hide the rdsb in my stand

Hang Loose

Baden:bum:
 
If you have no sump, then the bucket needs to be higher than your tank, with the MJ1200 pumping from your tank up to the bucket then draining by gravity back to the tank.
 
Even if you were to completely seal the bucket I do not believe a MaxiJet could push the water through the bucket and back out fast enough, if at all
 
If the bucket is sealed, and the "system" is full of water, then the "head" is zero.

Think about it for one minute.




> Barry :)
 
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