I have 4 RBP's in a 55 gallon grow out tank. The Red bellies are approx 4-5 inches apiece right now. I have a magnum 350 and a penguin 350 on my 55 gallon right now. Is that ok? too much? too little? The fish look like they are really happy and healthy, but i was just curious if my filtration amount was in the right ball park.