OK, been at this for a few years now and "knew what I was doing". Every year my CYA is low and it takes about 3 lbs to get to the level I need. Didn't test this year, just added 3 lbs. In short, CYA is higher than I wanted, right at 100. Don't usually cover my pool, keep the leaves and such out, but it usually gets pretty green every year (and cleans up beautifully). Never been a problem... just balance, pour the chlorine to it and filter, filter, filter. Was taking the same approach this year. It's a little harder this year because of my CYA level. pH is 7.5. T/A is right at 90.
I've got the TF-100 test kit. Chlorine should be high (55ppm ish), but when I test and add the DPD, it goes light pinkish for a few moments and then back clear. If I start adding the FAS/DPD drops, it will turn a little pink and with enough drops, back to clear. But if I continue with the CC test, it is registering 10 - 15. Never seen those kind of CC levels. It's almost like my kit has been pranked.
Also, added a 1/2 cup of DE to my skimmer to help with the filtering (new sand last year). In the past, I needed to backwash often when I first started this process. I'm not getting much increase in pressure at all.
I'm still a nice dark green, which is really surprising given my chlorine levels. Is the CYA just too high to let the chlorine work?
16 X 32 with vinyl liner
Hayward sand filter