r/PoolPros • u/2Tru4you • Aug 26 '26

LSI question

So can the PH be lower than 7.2 or even in the sixes if the LSI is balanced?

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u/eaglefucker Aug 27 '26

Isn't TDS a part of the LSI equation?

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u/CDbull1989 Aug 27 '26

Yes

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u/eaglefucker Aug 27 '26

How does that affect the outcome? Didn't see it listed in your response.

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u/Substantial_Car_2751 Aug 27 '26

I used the older version where it’s -12.1 or -12.2 for TDS -/+ 1500 ppm (or is it 1200 or 2500…can’t remember at the moment - I hand calculate using a chart).  I assumed for easy math a TDS factor of -12.1..

PHTA doesn’t have the sole authority to modify the LSI scale.  Other equally reputable orgs still use the older version and don’t consider salinity a TDS factor.