I am still trying to figure out the magic bullet to having crystal clear water. I have 6 tanks, all using AquaClear 50 and 70, all with basic AquaClear media, none have carbon, all stocked with the same bioload, same fish species, same fish size, all fed the same diet, all on the same light timer, all same LED
light fixture. However 4 of my tanks are crystal clear and 2 are slightly cloudy. Two of the tanks have plants in flower pots, but 1 of the 2 planted tanks is cloudy. I have even done 80% water changes to make all tanks become crystal clear, but after 1 day the two problem tanks become slightly cloudy again. No medications, no sick fish. No ammonia or nitrites, and 20 ppm
nitrate in all tanks. I don't understand the cause of the cloudiness in the 2 tanks. One of the cloudy tanks even has a slightly lower bioload than some of the crystal clear tanks.
I've considered the possibility that some fish have diabetes and are urinating a lot and the filters cannot handle fish urine. It's far-fetched but I can't think of any other explanation.