Does anyone know how to test gallons per hour of an airline/sponge filter? Im interested in seeing exactly how efficient these filters work. I saw an lfs that used nothing but these kinds of filters, 1 per every 5 gallons. His fish are healthy, and the ones i bought from him have lived happily in my tank without causing illness for quite a while. Makes me wonder - keep it simple stupid? is the one of the most simple filters good enough?
