I have approximately 38,000 gal in-ground plaster pool and I'm struggling to maintain a decent FC level with an IC40.
I originally had a Hayward aquarite with T15 cell with 1 hp pump at 8 hrs /day and FC levels were always good at around 3-4 PPM
I ripped that system out and renovated with Pentair EZtouch with built in IC40, intelliflow VF, and intellichem and screenlogic. I set up pump to run low flow 23 hrs/day for 1 complete turnover and set intellichem to run the SWG for 12 hrs/day. Water was balanced, salt 3200, CH 340, TA 70, PH 7.6, CYA 30. FC would never be over 1 PPM unless I shocked. Walls would green up if I didn't shock. Increasing the SWG runtime to 23 hrs/day helped a little but the FC should be much higher. ORP always read low around 500 but that's from the SWG effect. The longer I ran the SWG, the lower the ORP reading on the intellichem.
I just chalked it up to the sun destroying the FC due to low CYA required for the intellichem to "work accurately" (which it didn't).
This year I decided to experiment a little. I dissolved 25 lbs of CYA (first mistake) before measuring existing CYA. I wanted to see if the FC would improve its longevity with a higher CYA. So now I'm between 90-100 ppm CYA which made the intellichem useless. the ORP reads at over 1000 with zero FC in the water. At that level the SWG will not dose at all. My new FC target with this much CYA is now 5 PPM. I removed control of SWG from intellichem and now have % control from eztouch. I set to 100% @23 hrs/day and let it run. After 4 days the fc was at 1.2 PPM. I am stumped at this point. I wait for night to shock the pool. Here is where it gets interesting.
I turned on the pool light so I can see what I'm doing and there a jet right above the light spewing a milky cloud of bubbles which is normal SWG output. Suddenly it decreases to a few and then no bubbles. I check the IC40 and the output lights are still on at 100% all systems go. The bubble stream came back about 5 1/2 minutes later and made bubbles for 4 minutes and stopped again for another extended period if time. No status change on the IC 40 panel. This cycle repeats constantly so 100 % output is not continuous. It is more like 40%. This could have been my problem all along. Anyone familiar with this problem and how to diagnose?