Filtering question.

undergravel filter would not be necessary. Canister filter is basically the same as a power filter except its in a canister and not hanging off the back. As long as the canister is rated as being capable of filtering a tank your size it should be okay.

UGF's can be a big problem if not used in a reverse flow configuration. That is pumping the water into the UGF and up through the gravel or substrate. If used in a normal configuration where water is sucked into the gravel and then to the filter all the waste goes directly into the gravel and will get traped there and decay causing a huge nitrogen problem. JMHO.

Reverse flow though does make for a great biolgical filter as you feed the gravel or substrate with oxygen rich water that will grow a huge bacterial colony.