Liquid chlorine vs dichlor now that CYA's parked at 45

Started by Priya Raman · · 1 reply
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#1
Been going back and forth on this all season. CYA's been sitting at 45 for weeks (screen enclosure means barely any splashout to dilute it, so it just sits there), FC 4.5, pH 7.6, TA 80. Switching to straight liquid chlorine would let CYA drift down slow through backwashing and topoffs, but then I'm buying jugs constantly and watching pH creep since liquid pushes it up a little each dose. Sticking with dichlor here and there keeps things simple but I know it's basically why CYA is where it is in the first place. Anecdotally my ICO shows tighter FC swings on liquid days versus dichlor days but that could just be dosing timing, n=1 and all. Curious what people are actually doing long term once CYA plateaus like this instead of chasing a dilution drain.

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#2
Priya, once CYA plateaus like that the answer is just switch to liquid full stop and let dichlor go entirely, don't keep splitting the difference because every dichlor dose is another 6ish ppm of CYA you're never getting back out except through drain and refill. The math on that stuff is unforgiving, it's roughly 1 ppm CYA for every 1 ppm FC you add, so if you're still dosing dichlor "here and there" your 45 is going to keep creeping regardless of what the liquid days are doing to dilute it.

The pH creep from liquid is real but it's a much smaller thing to manage than CYA once it's built in, on my pool I add a little muriatic every week or two to walk it back down and that's the whole tradeoff, it's not even close to the hassle of babysitting an ICO whose swings are actually being driven by CYA riding higher than you think. Your n=1 on tighter FC swings with liquid isn't noise by the way, that's just CYA math showing up in real time, less buffering means the sensor's actually reading closer to what's happening rather than a moving target.