it sounds like its a little bit over crowded, keep my 125 crisp with 2 350 magnum canister filters, one is bio and one is carbon filled, both are wrapped in towel like filter material, i only have a motoro pup and a 7 inch arow in it. the fish are extremely happy and the water is unbelievably clean/clear and crisp haha.
if the water is foggy i would suggest more carbon but ive heard that that is not always safe
if the water is foggy i would suggest more carbon but ive heard that that is not always safe