Today I went to the pool to take some measurements for the winter cover. The solar cover has been on pretty much permanently for 3-4 weeks. I lift it to take a look and lo! and behold, GREEEEEEEEEN! Well, you know what you get after a summer of being cocky to yourself about great test results? A green pool towards the end of the season. It's getting cold here, and so swimming is pretty much over, but the pool isn't closed.
So first thing I did was test FC and CC. FC was at 6.0 and CC 0.5. 0.5??!! That makes no sense to me. After reading everything in pool school more than once, if anything I was fully expecting some CC!!! Nonetheless, I began to SLAM. I did not do a full test, as I have been testing all summer and my results have been pretty consistent. I will definitely do a full set of tests tomorrow... I started at 1400 today and maintained FC to 16 by testing about every hour or so. My CYA has been rock solid at 50, slowly dropping to 40 last time I tested it, about a month ago. TA has always been 60 and CH 100.
So. What happened? I'm trying to figure it out so I don't repeat the same mistake later. Did I leave the solar cover on too long? Was it the Borax I added about a month ago to bring the pH from 7.2 to 7.6? Or was it the fact that a couple days ago I noticed on my P4 panel, the "check system" light was ON. I'm not sure how long it had been ON, but I reset the system and it started to chlorinate. The light hasn't come back ON. But would my FC be at 6.0 3 days later? Was it not chlorinating for however how long the check system light was ON?
As it stands now, I brushed and brushed, and the pool is uber-cloudy. But I just tested and my FC was 20 (was targeting 16 but I also started the superchlorinate to help keep FC levels up throughout the night) and the CC was still 0.5! My pH is at 8.2, could that be a side effect of too high FC? Should I worry about pH later, once the water is clear and I pass OCLT?
I should've known better than be proud of my clean pool this summer... Something was lurking to come and get me.