User Guide

types of drinking water products. Testing the TDS of bottled water is similar to testing tap
water. Distilled water will have a TDS of 0. Spring water, purified water, and filtered water, on
the other hand, can contain a high level of minerals and salts, which affect the TDS. It is not
unusual for bottled water to have a TDS of 100 ppm or higher.
TDS and aquariums
Freshwater tropical fish are native to a
variety of aquatic biotopes. South
American river fish and plants thrive in
water containing almost no minerals,
thereby having a low TDS. African lake
fish live in high TDS water containing
lots of calcium, sodium, and chloride. If
you have fish, it is best to keep them in
a solution of water with a TDS similar to
their natural habitat. A high TDS can wreak havoc by causing cloudy water that sunlight cannot
penetrate, therefore harming the process of photosynthesis for aquatic plant life. It can also
affect the growth of the fish, impact their breathing, and make them more prone to disease. So,
the TDS measurement can be used to decide the frequency of changing the water in a tank.
Examples of an ideal TDS range for aquarium fish and ornamental pond fish
 350-400 ppm African lake cichlids
 200-500 ppm Goldfish, Japanese koi
 100-300 ppm Guppies, Swordtails, Mollies, Barbs
 10-100 ppm Angelfish, Discus, Neon tetras
Testing TDS in aquarium water
Simply place the meter into the aquarium, preferably near flowing water. Hold the TDS meter
until the reading stabilizes or locks in. Thoroughly rinse the meter after each use. Aquarium