Archive for the ‘TDS Meter’ category

TDS Meter

July 8th, 2014

TDS meter is an equipment which is used to measure the amount of Total Dissolved Solids i.e. TDS in an aqueous state/water. The instrument/equipment is convenient, accurate, portable and easy to operate, especially for field measurement.

What Are Total Dissolved Solids?

Total Dissolved solids” refer to mobile charged ions including minerals, salts, metals, cations or anions dissolved in given volume of water. This includes anything present in water other than the pure water (H20) molecule and suspended solids. (Suspended solids are any particles/substances that are neither dissolved nor settled in the water, such as wood pulp.) TDS is expressed in units of mg per unit volume of water (mg/L), also referred to as parts per million (ppm).

Principle of TDS meter

A TDS meter is based on the Electrical Conductivity (EC) of water. Pure H20 has virtually zero conductivity. Conductivity is usually about 100 times the total cations or anions expressed as equivalents. TDS is calculated by converting the EC by a factor of 0.5 to 1.0 times the EC, depending upon the levels. Typically, the higher the level of EC, the higher the conversion factor to determine the TDS. While a TDS meter is based on conductivity, TDS and conductivity are not the same thing.

Applications of TDS meter

  • To identify the Taste and effect of TDS on Health


High TDS results in undesirable taste which could be salty, bitter, or metallic. It could also indicate the presence of toxic minerals. The Environmental Protection Agency (EPA) recommended maximum level of TDS in water is 500mg/L (500ppm).

  • To meaure Hardness

High TDS indicates Hard water, which causes scale buildup in pipes and valves, inhibiting performance.

  • For the aquatic life

A constant level of minerals is necessary for aquatic life. The water in an aquarium or tank should have the same levels of TDS and pH as the fish and reef’s original habitat.

  • To measure the Hydroponics

TDS is the best measurement of the nutrient concentration in a hydroponic solution.