[tillysreef]

hi all
my sump is 2 tier basically and where my wier outlet comes down i have a tank basically 12 inch square, my mce 600 skimmer hangs on the outside of this and its currently filled with some LR but mostly larva rock that was in my tank originally, it overflows into the next sump which has my refugium and then return in, this area also has LR in. would it be an advantage to turn the first section into a dsb as it gets good flow etc, if so what to use and what sort of depth?

[Dave.I]

Yes well worth it.I use sugar fine aragonite.Its round so provides better flow through the sand bed.The normal sharper more jagged sands can compact and restrict flow a little.I would aim for 7 inches or more and plenty of flow over the surface.If its too much flow just put some larger grain sand on top.

Dave

[tillysreef]

that seems very deep for sure, going to try it though

[Blacktip]

Larva rock I believe drops pH.
Live rock in the sump, some people consider, is not a good idea is it gets dirty preventing good flow around the rock.
Depth of the sand depends on the size of the sand particles. If using oolitic sand then it should start to work at 3" and gets better the deeper you can make it.
If adding sand to mature system it might be worth keeping an eye on Mg, Ca and KH.
Mr Simon G site has very good info on DSB along with Ron Shimek's.