On Wed, 04 Dec 2002 02:30:01 GMT, "kush" wrote:

That's not really true. Power filter or UGF, it's still a closed system and
waste products remain in the system until broken down by bacteria and
utilized by the plants or removed through water changes (or wrung-out of
filter pads; is that what you mean?).

yes, with a power filter or canister filter, you can remove and clean
the media. With a UGF filter, the waste remains in the substrate
until it completely breaks down.

To work properly, a UGF is meant to be vacuumed very well, very
regularly. In a heavily planted tank, this isn't possible, so all
the waste remains in the tank until it completely breaks down.

Chuck Gadd
http://www.csd.net/~cgadd/aqua