Right now it is probably a combination of overfeeding (which leads to extra poo) + not enough filtration + too much light + water not changed frequently or enough water changed in possibly too small a tank or too over stocked a tank....


Can you give a run down to remind us about size in gallons/liters, how many and how large the ACF are, type of filtration, feeding, how often and how large the water changes, how many/types of live plants, lighting type and duration....