Re: Saturation Index (Langelier, etc.)
The LSI as it is currently applied as 'gospel' along with TDS measurements in most pool stores are bogus measurements. While in theory it holds some value it is a most abused measurement today. It's main purpose seems to be to allow pool stores to sell unnecessary chemicals to customers. The store I work in has disabled the LSI function in our software and we rarely take a TDS measurement (We have a MyronL TDS meter...pretty much industry standard). This measurement is so abused in real world situations it is not funny. Taylor's watergram is useful as a rough guide but it's very construction does not allow for accurate results. It is really a 'ballpark' device. In the real world the temp. of a pool will vary by several degrees over the course of a season or year. My pool is open year round and my temperatue will vary from a low of about 40 deg. to a high of 90 deg. Does that mean I have to change my chemical balalce with every temperature change? Or should I shoot for a 'happy medium' that will keep my pool 'balanced' for the majority of the year? There are no easy answers to these questions. In real world applications things don't occur as they do under controlled conditions. I beleive the goal is to find measurements that will produce good results under the varous conditons that occur that are easy for the average pool owner to implement. The LSI has not proven itself to be one in real world conditions!
Retired pool store and commercial pool maintenance guy.
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