Discounted Kooler Max RO Water System HK-120The KoolerMax HK 120 is a 4 stage reverse osmosis (RO) water filtration system. System Capacity & Purpose: The unit is designed for heavy duty, high flow applications such as greenhouse gardening, car washing, or filling aquariums, rather than just home drinking water. Performance: The 150 GPD rating allows for rapid filling of reservoirs. It operates effectively on standard tap water pressure, though some models, like the HK120P, include a booster