proper mud/sand depth help

[spamreefnew]

main display tank will have 1/2' to 1" medium black established(3yr) sand.
my new sump is an "ecosystem" style. the fuge section measures 9"x10".
i think i will use a 50/50 mix of white fine sand and reef mud. so how deep should it be? most of my reading says 1" or 2" what say you?

 

[HighlandReefer]

What is the purpose of adding reef mud to your system other than wanting to plant seagrass in it?

I don't think adding sand in your sump will do much, except to harbor organic matter in it (possibly more nitrate production by aerobic bacteria). If you can put light over the sump, you may get more benefit from raising chaeto or some other macroalgae in it.