1. Water treatment instrument kit 2. TDS meter + water electrolyser 3. Identify water ... level 4. Easy to operate 5. CE Water treatment instrument kit: TDS meter + water electrolyser 1. What is TDS?Total ... regulation, aquaculture, hydroponics, agriculture, colloidal silver, labs & scientific testing, pools & spas, ecology testing, boilers & cooling towers, food processing, physics & chemistry teaching ...