CH Test started at around 190 when pool was first filled in December, rose to ~280 within the first 60 days due to the plaster curing, and has mostly stayed between 270-320 from Feb - May. I saw some calcium scale building up on the SWG last month and lowered ph to counteract(-CSI). This solved that problem, but over the last two weeks when I've done the CH tests what I see is that right from the start the R11 solution turns the vial only very light green, and then the vial rapidly turns almost transparant with just a blue tinge at ~360 - if I keep adding drops, the water color only changes by the most tiny amount and is itsy bitsy more blue at ~450 (but still mostly still transparant).
So, I'm wondering if my chems have gone bad, do I need to keep adding drops to see if the color changes further to finally something more blue, or which CH result should I trust 360/450/etc.
I do note that we have quite a bit of evaporation with air temperatures in the 80's and water temperature held between 85-90 degrees. The autofill no doubt has had to add a bunch of water and our area has spikey tap water ch levels so I expect gradual increases in CH...360 seems believable..450+ would be a stretch.