Reverse Osmosis TDS Handheld Digital Meter Water TesterUSAGE: Used for domestic reverse osmosis systems, aquarium or water fed pole users and other systems to ensure accurate water quality hardness. It calculates hardness or total dissolved solids reading of the water. DESCRIPTION: Dip the TDS meter down to the indicanted pointer level into a water sample. The meter will give you a digital reading in PPM (Parts per million) of the total dissolved solids in the water. The higher the reading, the harder the