What kind of tank is it? How big? Korailia aren't as good as they are rated for, budget minded cheap water movement, Chinese shit. SW trade gave up on them 5-7 years ago due to reliability issues. Better off drilled tank with sump and a quality circulation pump. Danner/Mag or go home. Powerheads are for supplement flow not main turnover. You need to turn a r tank 10x per hour PLUS filtration!