TDS Meter Aquarium Water Tester - HM Digital

Description TDS-4TM: Aquarium TDS Meter with Digital Thermometer The TDS-4TM handheld meter is ideal for testing TDS and salt levels of freshwater aquariums and ponds. It can also be used for testing water filtration and purification systems, such as RO and DI, to know when to changes filters and membranes. Pocket size makes it ideal for portability and storage. Hold Function Auto-off Function (After 10 min.) Factory calibrated with 342 ppm NaCl solution   What is TDS? Total Dissolved Solids (TDS) are the total amount of solids, including minerals, salts or metals, dissolved in a given volume of water.  A TDS meter measures the total amount of mobile charged ions (based on conductivity) and expresses the TDS quantity in parts per million (ppm).  TDS includes any inorganic element present other than the pure water molecules (H20) and suspended solids.   TDS and Your Fish TDS is important for osmotic regulation and hydration.  If the TDS levels are not correct, a fish m