Also, digital photometers are not immune to the blunders of the people using them. Improper handling or infrequent replacement of the water-sample vials can cause false readings, as reagents or elements of the pool water itself can cause staining. And with the handling of reagents of any form can come a variety of other complications. In DiSalvatore's case, the alkalinity test on her digital units requires a full minute's worth of commingling of the water sample and the reagent. It sounds simple, she says, but as many pool operators can attest, many part-time pool employees have a knack for overlooking seemingly mundane testing details. "We have part-time lifeguards who have little or no certifications or qualifications as far as operating an aquatics facility or a pool, and they are able to use the system pretty easily overall, without much error," says DiSalvatore. "That is, as long as they are able to wait that full minute for that one reagent."
