Is there any way to figure the gpa of a sponge filter that is run on an air pump? I am going to use a sponge filter in my Betta tank, and I want to turn the air down enough that it's not creating tidal waves, but I want to make sure there's enough filtration.
I think as long as the sponge filter is rated to fit the size of the aquarium and the air is moving through it freely it does not have to be at any certain rate. The filtration is a little different with a sponge filter and I do not think that it is ever figured that way just in the capacity of the sponge. If the sponge is rinsed when needed and maintained according to instructions then it should not have to be running at a tidal wave speed. I have mine all just comfortably bubbling and my tanks are doing fine and the levels are great on the water so other than the first day or so when the Bio-spira was getting settled in and I had a little amount of ammonia and nitrites [it does that every time no matter the type of filter] I have had a much more stable tank with these than with the bio-wheels. They are not nearly so touchy.
They only thing I was disturbed about on my filter when I got it was it said in the instructions to rinse it weekly under running water. NOT there would go the bacteria in a great big hurry. So I am just going to swish it lightly in the used tank water when it needs it.