>My tanks use mechanical filtration only, and the mechanical filter is a sump
>tank with "dead water" pockets.  I just let debris settle out into the dead
>spots in the settling tank and siphon it out every few months.  My smallest
>tank has no active water movement of any kind and has been running successfully
>for several months now.

How are you getting the water to the sump? I use a DYI trickle filter and
have thought about removing the bio media, but when I removed the bio tower
the water rushed into the sump with such force that I was sure that it would
deplete the CO2 which I am adding. Also what are you using to divide the
sump into "dead water pockets"? I have 2 sections in mine which is divided
my an open cell sponge held inplace with 2 pieces of egg crate. I have
sponge filters in the prefilter to keep the leafs and such from getting into
the tower.

I woud be interested in more detials on your design.