regarding the play sand, it actually doesn't get into the filter once it's settled unless you really go crazy in your tank or something like that. i'm using it now, and even when doing light digging (searching for
MTS and such) in the tank, it settles pretty quickly.
if you're really concerned about getting sand into your filters, you could also put a sponge over the intake to prevent sand from getting in. decreases the frequency that you have to clean your filters, but you have an additional sponge to clean occasionally. also an additional place for bacteria to grow
