The principle of the TDS meter is a saline meter.
The principle of operation of the device is based on the direct dependence of the electrical conductivity of the solution (current strength in a constant electric field created by the electrodes of the device) on the amount of compounds dissolved in water (parts per million, ppm; 1 ppm = 1 mg/l).
TDS (Total Dissolved Solids) is the total amount of all impurities dissolved in water - salts of alkaline earth metals, mainly calcium and magnesium. There is a direct dependence of electrical conductivity on the amount of hardness compounds dissolved in water, this is the basis of the principle of operation of the TDS meter.
Application area
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measuring the level of salt in tap water, wells, wells, aquariums
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assessment of the total hardness (dH, f, mmol/liter, meq/l) of tap water in wells, wells, aquariums
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checking the efficiency of household purification systems operating on the principle of reverse osmosis
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checking the efficiency of household water filters
Why measure the hardness level?
There is no perfect water in nature. Even pure artesian water is often characterized by a high content of calcium and magnesium salts, that is, increased hardness.
Water hardness affects not only animals, plants and humans, but also equipment and water supply systems. Due to the geological and soil characteristics of a particular region, or due to anthropogenic pollution, water also often contains foreign impurities - mineral and organic.
In order to improve the quality of the water used, first of all, it is necessary to measure the level of impurities.
Salt meter TDS 139 is specially recommended for measurements in aquariums, swimming pools, cooling installations.
Assessment of the total hardness of water
Produced by converting mineralization to a hardness unit:
1 dH = 17.8 ppm,
1 f = 10 ppm,
1 mEq/L = 50.05 ppm CaCO3
Calibrating the TDS meter
TDS 139 refers to single point TDS meters. Single point TDS meters are usually calibrated with a ppm solution of 1382. Immerse the TDS meter up to the maximum level in the calibration solution at 25°C and stir the solution for 30 seconds. Wait for the measurement to stabilize on the display. Calibration is carried out by turning the adjusting screw clockwise and counterclockwise until the readings of the device coincide with the value of the calibration solution. The rotation of the screw moves the TDS line parallel to the axis of the “real TDS value” and the task of calibrating the TDS meter is to achieve the coincidence of these lines. In chemical laboratories, it is supposed to calibrate the TDS meter every 2 weeks. For hydroponics, calibrating the TDS meter every 3 months is sufficient.
Using a TDS meter
Never immerse the device directly in a container of solution. First, take 20 ml of the solution from the container, for example, using a disposable syringe and place the taken sample in a clean glass. Then lower the electrode of the TDS meter into the glass, stir gently and leave for 30 seconds. Turn on the TDS meter. When the TDS meter readings stop changing, you can read the readings.
IMPORTANT!:
Significant deviations in measurement or lack of stabilization of readings can be due to lack of calibration, dry electrode or weak battery charge.
Battery replacement.
ATTENTION!:
If the device does not turn on, the display goes out or the display readings are unstable, replace the batteries, paying attention to the polarity.
Carefully detach the upper black part of the TDS meter housing, which has the power button, and remove the batteries. When installing new cells, the type of batteries must be strictly observed.
Batteries: 2 pcs CR2032 batteries.