Review on Aquapapa 4X Bio Sponge Filter: Ideal Betta Fry Aquarium Solution for Tanks up to 15 Gal by Doug Daniels

I couldn't believe these little filters would keep my aquariums clean but considering the price I decided to give them a try. Boy am I glad I did that. My water stays crystal clear and I no longer need filter media. I put two in my 20 gallon tank, one in each corner, and the water stays perfect. Very easy to clean and I can keep the good bacteria in my tank. I have since ordered 4 more packs and changed all the filters in my tanks.