This begins my 3rd year maintaining our pool and I've done well (due to the Forum, thanks), but I'm STILL confused. We have an Aquarite SWG. Aquarite recommends a FC level of 1-3ppm. The first year, I maintained that FC level and had no problems whatsoever. Last year, I kept the FC level around 5ppm, (my CYA was around 30-50, which is below Aquarite's recommended 60-80ppm), and I had some trouble with the pH drifting up. So, my questions are:
1) Is a FC level of 1-3 ppm too low? (The liner mfg also recommends that level.)
2) Do high FC levels cause the pH to drift up?
3) I understand how CYA affects the "shock" FC level, but I don't understand what CYA has to do with maintenance FC levels, other than keeping the CL from disappearing too quickly. In other words, with a CYA of 30-50, why is a higher FC level required than if the CYA is 0?
4) Why does Aquarite recommend the higher CYA levels? According to the "Best Guess" cya chart, with a cya of 80 I'd have to maintain FC of around 8, which I'm afraid would be hard on my liner.
5) How can Aquarite recommend a cya level of 80, and a FC level of only 1-3ppm?
Thanks!
PAT