Holy Chlorine, Batman!!

[PoolDoc]

Yikes. What was he thinking?

With most test methods, there's no way to determine 44 ppm. OTO will be dark orange at that level; DPD tabs will be clear. So, he may have thought his chlorine was too LOW!

I forgot to add that that his pH was 7.2 the second time I tested for him (10 days after the 44 - FC.) I have no idea how that was possible.

The Taylor reagents are stabilized against chlorine, but not to 44 ppm. As far as I know, the only reliable method of testing pH, when the chlorine is that high, is a RECENTLY CALIBRATED pH meter.

Ben
"PoolDoc"

[waterbear]

The Taylor reagents are stabilized against chlorine, but not to 44 ppm. As far as I know, the only reliable method of testing pH, when the chlorine is that high, is a RECENTLY CALIBRATED pH meter.

Ben
"PoolDoc"

DITTO THAT, Ben! At that high a chlorine level just about all the phenol red would probably have converted to chlorphenol red which is yellow at a pH of about 5.0 and turns purple at a pH of about 6.6 with shades of orange, red and red-purple in between, similar to phenol red from ph 6.8-8.2. So, if the pH appeared to be about 6.8 (yellow orange with phenol red test block) it was probably MUCH closer to about 5.2!!!!!!!!!!!!!!!!!!!!!!!!!!!) Trichlor is VERY effective at lowering pH, as we all know too well
Once the chlorine level started to drop to 22 ppm then the sodium thiosulfate in the pH indicator might actually have had a chance to kill some of the chlorine and less of the phenol red would convert. Hence the apparent jump in pH. I would have to guess the pH was STILL probably at or below 6.0 however. The indicator color would be a mixture of both the phenol red and the chlorphenol red in some unknown proportion at this point so the pH reading is still probably bogus.