Didnt realize how much a big rainstorm drops your salt level

Started by Dana Whitfield · · 2 replies
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#1
We got hit with a bunch of rain last week and I noticed the AquaRite was flashing low salt a couple days after, went from around 3200 to under 2700. Never even crossed my mind that rain water dilutes it that much, I guess I always pictured it just raising the water level a little not actually watering down the salt. Had to add a couple bags to get back in range. Anyway just surprised me since nothing else about the water seemed off, no cloudiness or anything, the cell just started complaining. Anyone else keep an eye on salt after big storms or do you just wait for the panel to tell you.

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#2
Dana, before the salt math even makes sense, how much did that storm actually raise your water level, like did it overflow the skimmer or just come up a couple inches. Because the dilution effect scales with how much new water got added relative to your total volume, and going from 3200 down to under 2700 is a pretty big swing, that's over 15 percent, which on a 20k gallon pool would mean something like 3000 gallons of rainwater came in. If your pool's smaller or bigger that changes the picture, but that's a real lot of rain unless you've got a smaller pool than that. Worth checking because if the drop is bigger than the actual dilution accounts for, something else might be going on with the cell reading itself.
#3
Alan's math is sound but there's a piece missing, if the pool overflowed even a little out the skimmer or the deck drains during that storm, you lost some of the salty water right along with gaining the fresh, so the dilution number looks worse than plain rainwater coming in would account for. Doesn't take much overflow to skew it. I don't run salt myself, stuck with trichlor and a weekly shock for thirty years now, but I've got buddies with the salt setup and every one of them says the same thing after a big rain, check the water level against the tile line before you trust the cell reading.