Anyone ever have DPD powder go bad while it still looks white?
I'm getting inconsistent free chlorine test results. On several occasions I've gone to test chlorine and found it way too low, and added enough to correct. Then, testing the next day, I find that the reading is higher than it should be, given the amount I added.
After a few scares, I have determined that sometimes when I add the test powder, the water doesn't get very pink, and the resulting test isn't going to report much chlorine. Dumping water, rinsing and starting over usually does the trick, though I occasionally need to try a third time.
Both DPD powder (Taylor R-0870) and R-0871 are last year's, but the problem sure seems to be occuring when I add DPD.
I have another, unopened DPD powder I'm going to try before I order another, but both it and the one I'm having trouble with were purchased at the middle of last year's pool season, and have been stored in my 70-80 degree house.
I'm also curious, why do vials of DPD powder have varying granule sizes?