i have a standard 55 gal with a 7 inch butti , an 6 inch mosiac gar , a 4 inch pike and a 4 inch catfish and a common pleco. I would like upgrade my filteration. i mean i plan on upgrading my tank to a 75 or 90 but in the mean i want better filteration . The filteration i currently have is the emperor 400 . it does 400 gal per hour. Any suggestion on what to up grade to .