I recently purchased a 120 gallon tank. It came with a Tetratec pf500 and 300. Now i have not hooked the filters up. I was just wondering if anyone out there had any experiances with these HOB "Innovative" filters with heater core inside filter. I have one fairly large oscar 5-6" and 3 smaller 3-4" oscars. this tank will be their new home. Oscars are very messy fish and i was wondering if these filters will withstand the fish as they grow. The filters are rated 500gph and 300gph. Or should i just go with a sump and ditch the aquired filters? If so what size of a sump.