DSB: 10" better than 5"???

[orangegoby]

need some marine scientist help here. DSB, is the deeper the better?

[MrClam]

Im not sure youre going to find a singular answer to that question. Some people argue that a DSB is pointless and does little for denitrification unless it is very large.

From what I can see most fans of a DSB setup are split. Some people try to counter the old tank syndrome by creating a very deep bed. The rationale is that over time bacterial mulm settles into the sand and builds up. Giving a deeper bed allows more time before the sand bed is exhausted. This is where you hear the 1'' per year saying.

Other people will argue that the nitrifying bacteria are not truely anaerobic and require some oxygen to function properly. If this is the case the 10'' bed will have almost no water exchange in the deepest 3-4'' and thus will be essentially useless.

I have never read a scientific study examining long term effectiveness of sand bed cultures of nitrifying bacteria (would love to if someone has one). However I do have some background in microbio and in so far as I know anaerobic bacteria are capable of functioning completely in the lack of oxygen. In addition I believe that gas exchange will occur in water even if there is little water movement (albeit very slowly). So I tend to lean towards the idea that a deeper sand bed will encourage better function in establishing a complete nitrogen cycle, but as I said I do not have peer-reviewed articles to back that up.

[bishopthomas]

Funny to see the trends in aquaria. When I got into the hobby DSB's were the way to go. I've always run completely bio, with only live rock and sand as filtration. I'm in the beginning stages of planning a new build out and will be using a sump and skimmer for the first time ever. I've kept tanks from 2-55 gallons over the last 10 or so years and they've all had DSB's. I have done many things the "wrong way" and for the most part have had relative success.

But as far as the theory of "the deeper the better" I don't feel that that's necessarily true. No real science to back that up, but just a hunch.

[orangegoby]

good discussion.

[snowcarver75]

I recall a study which says that 6" is optimal. Anything deeper/shallower is either less effective or not necessary. presumably this works with the average substrate size. Fine sands require less depth.

[calbert0]

Also consider the overall footprint or square footage of the sand bed.

If its 10'' deep 12" wide, and 6'' long its not going to do much benefit.

Now say it 6" deep 12" wide and 24'' long.... we are getting there.

Think in terms of total sand volume, dimensions, and flow rate. Not just depth

[cloyd A.]

I have a 125 with a 50 gal. sump/refug. The dt has 6" dsb and the sump has 4" of sugar fine. My cuc is various types of snails and a serpent star.The main thing is to keep the live sand "live" with all micro and macro critters possible. My tank has been set up since the mid 90's with nothing but natural filtration and water changes. It is almost all sps,a few lps,a couple clams.

Hopes this helps,

[thegrun]

Recent studies have shown the denitrating bacteria seem to populate the zone between aerobic and anaerobic, which is around 4" so anything beyond 6" would simply become a detritus trap.