I am so confused and frustrated, and I hope someone here can help me shed a little light on my problem. I am in Los Angeles and am getting my pool up and running for the summer. My pool is approximately 17,000 gallons and we recently had a FNS Plus 60 filter installed to replace a dead Pentair filter.
The pool is very old and in bad need of a replaster - we just purchased the house a couple years ago, but I am willing to be that this plaster is well over 25 years old. It is showing a lot of delamination and there is probably a little algae under some of the bubbled plaster, but nothing more than last year, and I had no real chemical balance problem.
Other than that, the pool is sparkling and everything seems to be in check, but my chlorine doesn't stick around for more than a day and a half to two days. Yesterday, I did a big chlorine shock using 2 gallons of liquid and one bag of Pro Side Super Shock Quick. Here is my information as of yesterday after the shock:
CYA = 87
Total Chlorine = 10
Free Cholorine = 10
Total Alk: 133
Adjusted total alk: 107
Total hardness: 300
After that test, I added 2.5 pts of muriatic to bring the pH down and retested this morning. Here is where I am as of today:
CYA = 90
Total Chlorine = 3
Free Cholorine = 3
Total Alk: 130
Adjusted total alk: 103
Total hardness: 292
My chlorine levels dropped 7pm in about 24 hours. And by tomorrow morning, I am willing to bet it will be at 0. I don't see any chlorine demand issues, and my conditioner is fine, so I have no idea what's going on. Also, I noticed that 2.5 pts of muriatic had no effect on the pH. So, I am not sure where to begin.
I did clean the filter completely - there was some algae, but nothing crazy, and it is completely cleaned out now, so I don't think I have algae depleting the chlorine.
Any help would be greatly appreciated, as I am out of ideas.