I'm interested in finding out more about sponge filters, specifically for a betta tank. Ours came with the whisper filter and I just can't stand it, plus it's only carbon. Sponge filters sound like a better alternative, mechanically/biologically, and it seems like there would be no issues with current and tail fins, and it would take up less space. Then I start reading and seeing they need powerheads? I couldn't find a powerhead for less than $25. Could someone give me a little bit of a rundown on all this or lead me in the right direction? Thank you.