this is just me put if you have a 90 gallon tank with a normal set up (Bio-load) i would have at least 720gph of filtration. I do believe take your tank size and times it by 8. My 90 gallon with a 4 inch Flowerhorn, 4 inch Jack Dempsey, 3 inch Cuban, 4 inch Red Texas, 6 inch firemouth, and 1 bushynose pleco maybe 4.5 inches. i have a Marineland C-530 plus Marine Emperor 400 and a 1050 circulating pump. that tank is maxed out. the red Texas is going to another tank along with the Jack Dempsey and firemouth. you don't have enough water turn over per hour.