Spa pH won't hold steady, drifts up within a day of dosing

Started by Karen Delgado · · 2 replies
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#1
Pool's fine, steady as always. Spa is the problem child right now. Dose acid, get it to 7.6, come back the next day and it's already at 8.0 again. Spa's a lot smaller volume so I figured it'd be more sensitive not less stable, but this is something else. Jets aerate it hard every time it runs even for ten minutes, and out here in this heat it's outgassing CO2 like crazy on top of that. Fill water's over 400 ppm calcium so I'm already watching LSI close, can't just let pH float. Anyone running spas in dry heat found a dosing schedule that actually sticks or is this just acid every single day and accept it. Not looking to automate it, just tired of guessing.

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#2
Aeration plus heat is exactly why it climbs back, seen it a hundred times on spas that run jets daily, you're basically degassing CO2 every cycle so pH keeps bouncing back up no matter how much acid you dump in. With calcium that high I wouldn't chase it daily, just dose smaller and more often, half the acid you're using now but twice as frequent, keeps LSI from swinging as hard between doses.
#3
Karen, our little 300 gallon tub does the same climbing act and I finally quit trying to nail 7.6 and just aim for the low end, around 7.2, knowing it'll walk itself back up by the next day anyway. Tampapoolguy's smaller-more-often idea matches what we've found too, Gene dumped a bigger dose in once trying to get ahead of it and about scared us with how far it swung the other way before it settled.