You guys can let me have it...both barrels...when I'm done, but I have an undergravel filter with the charcoal and filter floss at the end of the filter discharge tube. So...I have mechanical, biological, and chemical filtration from the one unit. My "current" is stifled by the charcoal/floss cartridge at the end of the discharge, the tank is cycled, and me and the bettas are happy campers! It's worked very well for me. Btw, this is on a 10 gallon tank with four 2.5 gallon compartments.
I still wonder sometimes if the undergravel filter is the "ideal" choice. If under the gravel you're harboring the "good" bacteria...what's to say that under there you don't have some "bad" bacteria as well? That's a question I've always had...if somebody has the answer...please spill it!