The home we bought several years ago has a 20,000 gallon pool with an Intellichlor IC40 SWG that never seemed to work correctly. It was always reporting insufficient salt, while the chemical tests kept showing there was plenty (3500+) of salt in the pool. So our pool service used stabilized tablets to maintain our chlorine levels for the past several years.
This year, we quit using the service and I'm trying to do it all myself. Looking around online, I found a reference that discussed steps for calibrating this SWG (it's a V1.6). [I'm disappointed that the pool service people never said anything about this. I'm also disappointed that, in several calls I made to Pentair Support about the IC40 "problem", none of the Pentair tech support people mentioned anything to me about calibration, either!]
Anyway, I followed the calibration steps from that post and, now, that IC40 has green lights and appears to be generating chlorine just fine! So I'm pretty excited about that!
My question, however, is about the CYA level in the pool. It tests at 110ppm (which I'm sure is due to the use of those stabilized tabs over the past several years), and the chart in the Taylor booklet says it should only be at 30-50ppm.
From what I've read, the "only" way to reduce the CYA level is to partially drain and refill the pool to thereby dilute the CYA concentration. However, I've also read that the unstabilized chlorine the SWG creates will use up some of the CYA over time. So, is it possible that, if my SWG is running correctly, I can avoid the drain/refill because the unstabilized chlorine from the SWG will use up enough CYA to bring its level down to somewhere in the 30-50ppm range?
If so, how long will it take? Or did I misread and the CYA actually doesn't get used up by the unstabilized chlorine, so I really will have to partially drain and refill the pool?