Profile: Water-testers.com is a distributor of dissolved oxygen testers, waterproof meters, portable combination instruments and conductivity controllers. We also offer PH, water testing, martini portable colorimeters, soil testers, total dissolved oxygen, pH and TDS for aquariums, food production, home water and soil testing for hydroponics plan growing. Our water-testers dissolved oxygen meters provide a great means of measuring 02 in systems. Our refract meters are precision optical instruments used for measuring concentrations of substances in aqueous solutions. They work using the principle of light refraction trough liquids.