I have a 28 gal with a biowheel type filter rated for 30 gal tank. Currently there's 5 serpae's They look happy. I have only been running the air pump when I'm home cause I read somewhere that the bubble were just for us. Fish really didn't need them. Is this true. Will I need to add air once I add more fish? Thinking of adding 2 pictus catfish and 2 rams. ???