On Wed, 11 Feb 2004 08:42:04 -0500, "BenignVanilla"
wrote:

My tank sits on a table of sorts and is 3 feet or so off the ground. There
is a staircase behind it so building a filter above it, and letting it
gravity feed back into the tank could be problematic. Letting the tank
gravity feed down to the filter and then pump back up to the tank would be
problematic (I think?) because then the tank can conceiveably drain.

One simple suggestion I might to keep from draining the tank, is a
siphon break on a pumped line can be a simple hole in the line/tube.
I pump from the pond filter up to a plant pond and to keep it from
draining/siphoning back I drilled a small hole on an angle toward the
flow just above the waterline at the outlet end and the flow draws air
and adds bubbles in the flow of water. When the pump shuts down the
air hole becomes a siphon break. I'm using 1 1/2" pipe in the pond, but
the same idea should work on a smaller scale.

Regards,

Hal