LSI calculator says I'm scaling but water looks fine, what am I missing

Started by Karen Delgado · · 1 reply
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#1
Ran my numbers through one of those saturation index calculators after topping off. Pool is 84 degrees, pH 7.6, TA 80, CH 380, and it spit out a positive number telling me I'm scale forming. Tile line looks clean, pebble finish looks clean, no new roughness in the spa. Fill water here is always over 400 calcium so I expect to run high but this is the first time the index actually flagged it instead of just being close.

Do you all trust these calculators or is temperature swing in Scottsdale summers just going to make this thing yell at me constantly. Not draining a full pool over a number on a screen without seeing an actual reason. Anybody had the LSI say scale and then nothing showed up for months.

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#2
Yeah I wouldnt drain over that, LSI is more of a heads up than a verdict especially with your CH already running high from fill water, it just means the math leans that way not that scale is actually forming that day. My fiberglass doesnt really scale so its not something I watch super close, but I know with pebble finishes a lot of it comes down to how fast that number is moving versus just being consistently a little positive. If tile and spa still look clean after all this heat id keep an eye on pH creep before I did anything drastic, since that alone can nudge the index without CH or TA moving at all.