What is total hardness (general hardness / gh), and what reagents do I need to measure it?


Total hardness is a measure of the calcium and magnesium ions in the water, referred to as the ‘hardness’ of the water. Some aquatic species prefer ‘hard’ water, and some prefer ‘soft’ water.

Total hardness can be measured using our Hardicol reagent (AP254) on a Palintest photometer. This will give a result for total hardness in mg/L CaCO3.

Sometimes the unit’s dH are used for total hardness. To convert this result to dH divide by 17.8, as 1 unit dH equals 17.8 mg/L as CaCO3.


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