what causes ch to rise?

Since you dumped the CYA in the skimmer, just don't do any backwashing, or grid cleaning for 1 whole week!
This allows the cya to fully dissolve, it takes a looong time. Watch for granules on the pool floor, if you see any, being they're acidic and can bleach your pool surface, vacuum them up and not to waste, but to filter so they'll dissolve.

I wouldn't necessarily turn off your SWCG, but turn it waaayy down. Keeping an eagle eye on it as the sun consumes FC, your bare minimum daily FC loss from oxidation of CYA + outgassing, without any UV present, is about 0.5ppm FC. How much above that you loose each day will depend on many factors, including water temp, air temp and sun UV exposure.

At this point, try to target the FC for your current cya in an SWCG chlorinated pool. At your current cya reading, that'd be an FC minimum of 3ppm and no less. So if you loose 2ppm per day, make sure the SWCG raises FC to 5ppm, preferably 5.5ppm (as a buffer) by the end of its run for the day. Taking into account bather load, or lack there of if the case may be.
 
Thread Status
Hello , This thread has been inactive for over 60 days. New postings here are unlikely to be seen or responded to by other members. For better visibility, consider Starting A New Thread.