stretching the vinyl or blistering the fiberglass. It also can cause bather discomfort through skin and eye irritation.

But large positive LSI numbers are nearly as problematic, most notably leading to scale formation. And beyond being unsightly, scale disrupts heater and salt cell operations, reducing efficiency at best, and halting all operations at worst. High LSI also causes cloudy water, metallic stains, and shortens filter runs.

It isn’t hard to calculate the LSI — a fairly simple formula is used that is familiar to many service professionals.

Nowadays, however, with the modern technology of smart phone apps, who needs to drag out pencil, paper, and conversion factor charts? As easy as it is to calculate, it’s easier still, not to mention faster, to simply plug the tested water balance parameters into any of a number of free apps, and let your phone do the work.

But to obtain those water balance parameters, the pool still needs to be tested, which is the subject of this particular issue of Service Industry News.

Special acknowledgement is given to the Association of Pool and Spa Professionals Fact Sheet, “Common Interferences in Pool and Spa Water Testing,” where some of the information contained in accompanying articles can be found.