Blue & Black Set for sediment and chloramine removal. Blue Filter: Used for removing sediment, which pre-treats hardness minerals to help prevent scaling on the unit’s plates for upto 1500 gallons. Black Filter: Chloramine is used as an disinfectant in municipal city waters. Chloramines in water, is a mix of chlorine and ammonia. It is dangerous when used in aquariums and ponds and dialysis machines.