Review on AQUANEAT Sponge Filter for Aquarium Fish Tank: Ideal for Betta, Nano, Shrimp, Fry. Includes Biochemical Filter, Airline Tubing, Air Pump Valves, Suction Cups. by Kurt Virden

When the bubbles come to the surface they stir up the surface water without creating a strong current. Surface slime was an issue and it was resolved. Maybe too much hassle, but for me simply pressing the sponge against the wall of the aquarium near where the bubbles reach the surface solved the problem instantly. No modifications required, this filter is currently working great for my 12 gallon tank. I only use a check valve since my air pump is below the waterline of the tank. This filter is perfect for bettas or other fish that are not good swimmers. I assume this filter creates too much surface noise for aquariums under 10 gallons as it shakes the surface of my 12 gallon tank too much. But it's just little things that don't really bother me. This filter is really good and I recommend it.