Hello; Not a "must" but I do run some sort of bubblers. I think of bubblers as a very good plan. Several benefits from having them.is it a must to have a airstone in a tank?
Hello; A basic way is if the fish gather at the surface. This can mean they need more oxygen and are gathering where the dissolved O2 is still getting into a tank. There use to be a test for dissolved O2 I made back in the 70's doing lab work and there may be a home version available.how exactly would one measure if the filtration agitates the water