I do not have a filter though, I have a heater and a small air pump for the tank. Gravel mulm would work better in that case?
Actually I am not 100% sure if it is a filter, I aquired it with the tank...It is an Elite Air Pump I'm pretty sure although it has a small sponge inside it, is that a sponge filter?
my 20 gallon has a whisper air pump but no sponge so I am a little confused by it :P
I will continue to read up on the fishless cycle :]