I've been testing my water with my TF-100 for well over a year. Before that I used the same Taylor pH test with the five pH levels (6.8, 7.2, 7.5, 7.8 and 8.2). I probably test for pH every other day and sometimes every day. So I've had a decent amount of practice over the last 18 months since we built the pool. I can clearly tell when the test result is 7.2 or 7.5. But anything above 7.5 is pretty much a guess. Although I've never seen the purple of 8.2, the result has gotten fairly dark red which I assume is around 8.0, but I'm not sure.
Also, I've tried to guess at 7.4 or 7.6 when the color seems slightly below or above the color of 7.5, but it's really just a guess. I don't believe I'm color blind--at least I've never had an issue before. Any ideas on distinguishing between say 7.7, 7.8, 7.9, 8.0, and 8.1?
Are they just guesses based on the shade of red you get? My problem is that above 7.5 the results all seem red to me, except some are slightly darker and some are slightly lighter. For CSI purposes there's a big difference between 7.7 and 8.1, but how can you really tell? Does 8.0 have a dark red/purple shade? Again, I don't recall ever seeing a purple tint to my test results.
This is important to me because maybe my water is leveling off at 7.8 to 7.9 and I just can't tell. Adding about 32 oz. of MA every 4-5 days is getting old.
Here are my latest test results if interested:
pH 7.5 (added MA yesterday morning)
CSI -.32 at 88 degrees.