pH keeps crashing a day after i dose liquid chlorine, alkalinity's fine

Started by swamp_tyler · · 2 replies
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#1
so the swamp's clear now, been running good for a few weeks, but every time i dump in liquid chlorine to keep FC up in this heat my pH drops like a rock the next day. total alkalinity's sitting around 90 which i thought was supposed to keep pH from bouncing around. i'm not adding acid at all right now, haven't touched it in over a week.

only thing i can think is the chlorine itself is doing it but i thought liquid chlorine was supposed to be high pH not low. using the Taylor kit to test so i trust the numbers. anyone else see this in the Phoenix heat where you're dosing chlorine almost daily. do i need to bump alkalinity up higher to buffer it or is something else going on

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#2
Whoever said it's aeration and CO2 outgassing not the chlorine is right, that's the big one, but nobody mentioned the heat is making it worse. Water that hot loses CO2 faster, waterfalls or spa jets running just speeds it along. Liquid chlorine itself pushes pH up slightly when it burns off, so if anything it should fight against a crash, not cause one. Bumping alkalinity to fix this usually backfires, you just end up needing more acid overall and the crashes don't stop, they just get less frequent. 90 is fine. If you're running fountains or the spa spillway a lot, try cutting that back and see if the drop slows down.
#3
Karen's right about the outgassing, dosing daily in that heat is basically constant agitation. My water splashes around the play pool all day and I don't chase a pH crash near as much as I used to when I had a spa jet running, cut that back before you touch alkalinity at all.