My filters suck up all the poop from the tank floors. It even does this on a 90 (tall) that has a HOB siphon overflow (not very low in the tank at all, takes water from the top) and an AC70 with both extensions on the intake.
I have 6 tanks, and only two have substrate and are fully planted, so don't require gravel vac. Regular gravel does not work this way. If you want substrate, go with a planted tank, using top soil as the bottom layer, and pea gravel (or other decorative gravel, I use pea gravel cos it's natural looking and cheap) over top of it. Here are more detailed directions. http://thegab.org/Plants/setting-up-a-walstad-natural-planted-tank.html
But if you already have fish in the tank, it is difficult to do this easily.
I have 6 tanks, and only two have substrate and are fully planted, so don't require gravel vac. Regular gravel does not work this way. If you want substrate, go with a planted tank, using top soil as the bottom layer, and pea gravel (or other decorative gravel, I use pea gravel cos it's natural looking and cheap) over top of it. Here are more detailed directions. http://thegab.org/Plants/setting-up-a-walstad-natural-planted-tank.html
But if you already have fish in the tank, it is difficult to do this easily.