Macherey-Nagel test strips for total water hardness, in one presentation.
932009
A semi-quantitative test strip for total water hardness, read on a reflectometer. Dip it, wait the stated time, and compare the pad against the colour scale on the tube.
DiaQuant strips read on a reflectometer instead of by eye. The colour scale is replaced by an instrument reading, which removes the two weaknesses of visual comparison: the operator's judgement and the operator's lighting. Hardness decides when a softener has to regenerate, and a softener regenerated by guess either wastes salt or lets hard water through to a boiler. The number is worth having exactly.
A strip gives a range, not a figure. That is enough for the great majority of decisions — dose or do not dose, discharge or hold, keep running or stop — and it gives the answer where the sample is, in about a minute, with no instrument to calibrate and nothing to carry back to a laboratory.
When a number has to be defensible — a regulatory report, a dispute, a limit you are close to — a photometer or a laboratory method is the right tool. The strip's job is to tell you whether you need one.
Sample after the softener and before the point of use; hardness measured at a tap includes anything the pipe has contributed since.
Supplied in one presentation.