Hi. I seen your post about sponge filters. Very awesome info! I'm looking into setting one up. With the sponge, is there a formula for how much surface area of sponge per gallon of tank? I got a 5.5 gal. With a single female betta. I want to grow enough BB to keep the water good but my tank can be viewed from all sides so I don't really want the sponge to be to big and destracting if you know what I mean.