Hi everyone! I am fairly new to aquariums I have had them in the past but recently inset up 2 tanks. One is an aggressive tank and one not 32 and 35 gallons both hexagon. In one tank I have a gourami, 3 barbs and a koi , this tank is great crystal clear and I think it is because of the koi, he eats everything off the bottom! The other tank I'm having difficulty with cloudiness! I have 2 bp's,an Oscar, a Pleco and a pink tail chalceus. I have done half water changes , changed the filter. Nothing seems to work! Any suggestions?