Medium-R series is standard double stage reverse osmosis system. With 2 stage pump, 2 stage RO membrane and buffer tank, system achieves stable water quality, little drain, and low running cost. Compared with single stage RO system, the quality of RO water is better, and the running cost is lower for less consumables replacement. Moreover, compared with simple 2nd stage RO system (1 pump, 2 RO membrane, without buffer tank), its system design is more rational, and the RO quality is more stable. Even though with the worse source water, the 2nd stage RO water’s conductivity also can stay 1-5μs/cm. Medium-RQ series is 2nd stage RO & deionized water system, with LCD controlling system, 3 way water quality sensor, timing and quality dispensing, stainless steel shell, built-in 2 set tanks (buffer tank and pressure tank). Its output ranges from 30 to 90 liters/hour. The 2nd stage RO water’s conductivity can stay 1-5μs/cm, and the deionized water’s resistivity is more than 10MΩ.cm, near to18.2MΩ.cm. It completely meets the requirements of general chemical or biological experiments for pure water.