Sand bed depth

[fender4string]

I posted this in the noobs section but figured I'd ask you guys also as you're the experts on the kind of tank I'm setting up and have all been extremely helpful to me during the whole research and planning phase.

I have 60 lbs. of sand currently in my tank (almost setup!!!!). Is that enough or should I add more?

System Info:
85 gallon RR
30 gallon sump/fuge (with 3-4" sand bed)
Octo Extreme 200 skimmer
80 lbs of LR (yet to be bought)

Stocklist:
Singapore angel
Valentini Puffer
One spot foxface
Kole tang
Picasso trigger

My main concerns are this-more sand equals better filtration so I'm worried I don't have enough sand. At the same time, I'm worried that if my sand bed is too deep that the picasso (having those trigger digging habits) will stir up the anaerobic bacterial layer in the deep sand, which is bad right?

[Recty]

The problem with a really deep sand bed and anaerobic bacteria only happens when it has sat undisturbed for a while and then like half or more of it gets stirred up. I cant remember what type of gas it is that goes into the tank, but it isnt good.

With that said, I knew none of that before with my 75g, I had a 4-6" DSB and about every 6 months I'd go through and stir it around, siphon a lot and try to clean it up a little, I never had any problems and I had some pretty delicate fish and corals.

I dont think the picasso will dig deep enough to make it matter, he will mainly work around in the first half inch to inch of sand.

Now the following is just my opinion....

Since you have a fuge, I assume you'll be growing some type of macro algae. In my experience, that macro algae far outperforms a DSB. A shallow sand bed is also much easier to maintain than a deep sand bed. If you arent doing a reef tank, I think you are MUCH MUCH MUCH better off going with a simple half inch to inch deep sand bed in your main tank, or even just no sand bed.

[Grouperhead]

Agree with Recty. Shallow sand bed in the tank, and dsb + rubble + macro in the fuge = success.