I am still struggling with the CYA test. When I first put stabilizer in the pool I measured with a goal of 40ppm. However, I was using 6000 gallons, the capacity of my pool and it was not completely full. So when I first tested and was getting 50-60 I figured that was why. I've since filled the pool to capacity and got a new sand filter, which had to be back washed several times at first to finally get my water truly clear, so I was having to replace that water for two or three days. The other day I noticed that my FC levels were seeming to fall a lot during the day, so I double-checked my CYA and it was showing 40. I figured that with the extra water and having to replace some from backwashing it must have brought the CYA levels down, so I backed off on the chlorine. While I was at the low end by the end of the day (hot sunny days, 2-3 people in the pool for 2-3 hours a day) it wasn't dropping as much. Figured I got the CYA dialed in, but since the 40 reading was new I decided to double-check it. The first test I got 60 again! Did it a few times got 60 each time. So started over with new reagent in case I'd messed up ratio. Now I was getting 40 (I could almost pour to the 30 mark before it disappeared). I tried this 4 times with new reagent (trying each test 2-3 times before changing mixture). Was getting the same thing 40, each time. Ok, figured the first test was a fluke. Decided to try again today since it was sunny, just wanting to have it confirmed the first time, instead I got 60 again.
I realized that what was changing between the readings was that both times I got the higher number I was using the reagent in the dropper bottles. The lower numbers was when I had to refill the droppers with fresh reagent from my larger bottle I keep in the closet. Now all of this reagent is kept in the house but the test kit goes outside for short periods. I'd refilled the dropper bottles to make it easier to pour in (the large bottle has no dropper) and to have it with the rest of my test kit. Could the fluid from the big bottle be being contaminated sitting in the older small bottles? Or could the temperature of the smaller bottles be getting warmer affecting the reading? I'm getting so sick of this test. 40-50 or 50-60 is no big deal but if its somewhere between 40-60 I pretty much have to treat it likes its 60 to be safe and feel like I'm just wasting chlorine, especially because it seems to fall quickly from the higher FC levels. Should I just trust the "fresher" tests?
Current levels
FC 6
CC 0
PH 7.4
TA 150
CH 260
CYA ???
I realized that what was changing between the readings was that both times I got the higher number I was using the reagent in the dropper bottles. The lower numbers was when I had to refill the droppers with fresh reagent from my larger bottle I keep in the closet. Now all of this reagent is kept in the house but the test kit goes outside for short periods. I'd refilled the dropper bottles to make it easier to pour in (the large bottle has no dropper) and to have it with the rest of my test kit. Could the fluid from the big bottle be being contaminated sitting in the older small bottles? Or could the temperature of the smaller bottles be getting warmer affecting the reading? I'm getting so sick of this test. 40-50 or 50-60 is no big deal but if its somewhere between 40-60 I pretty much have to treat it likes its 60 to be safe and feel like I'm just wasting chlorine, especially because it seems to fall quickly from the higher FC levels. Should I just trust the "fresher" tests?
Current levels
FC 6
CC 0
PH 7.4
TA 150
CH 260
CYA ???