Monitors provide people monitoring the purification process of their water an easy way to either get a quick display of water quality or to test actual water purity of feed water (input water) and product water (output water). Some of HM Digital’s products offer you up to 3 test points of the purification. The different applications where monitoring is important include drinking water filtration using Reverse Osmosis (RO) or Deionized water (DI), purification of water before adding nutrients to a hydroponics solution or even for the Aquarium enthusiast.