What You Can Measure with PoolWaterLAB®

The table below shows the chemical substances that can be measured with the PoolWaterLAB® photometer, along with their measurement range, accuracy, and cost per test. Each item (called a “parameter”) represents a specific chemical or property that exists in the water. Measuring these values does not determine water quality — it only shows how much of each chemical is present in the sample.
Parameter – The specific chemical or property being measured, such as free chlorine, pH, calcium hardness, or copper.
Range – The minimum and maximum concentration the device can measure for that substance.
Accuracy is a measure of how close the obtained result is to the true value. Unlike colorimetric or test-strip methods that rely on subjective visual color comparison, a photometer provides objective digital measurements with minimal human influence. For example, when measuring chlorine concentration, a photometer can record an exact value of 3.00 ppm, whereas visual methods can only estimate it as “approximately 3 ppm,” reducing the reproducibility and reliability of the results. Understanding the ±10% variation.
A ±10% variation indicates that the measured value may differ by up to 10% from the true concentration, primarily due to factors related to sample and reagent preparation rather than the instrument itself.
For example, when measuring chlorine, if the true concentration is 3.00 ppm, the photometer may display a value between 2.70 ppm and 3.30 ppm. Such variation can result from inconsistencies in reagent dosage, incomplete mixing, temperature differences, or timing errors during the reaction. These influences are attributed to the human factor in sample preparation rather than to limitations of the photometer’s optical accuracy.
Cost – How much you will spend on reagents for one test.
Reagent – The chemical used during testing to create a color change that the photometer can measure:
• Tablet – a small tablet that dissolves in the sample;
• Liquid – a reagent added drop by drop;
• Powder – a small portion of dry chemical powder that is mixed with the water sample before measurement.
A photometer measures how much light passes through a water sample after a reagent is added. The change in light intensity shows the concentration of a specific chemical substance, providing accurate and repeatable readings instead of visual color matching.