While I realize that most of the time our stock answer is that pH cannot be measured accurately during any condition where FC > 10; a few members have high CYA and restricted water options. Also some of us would like to know what pH is doing during shocking.
From what I understand, the phenol red tests for pH do not work reliably at FC > 10. So is there any way to reduce FC without destroying the accuracy of the tests available?
Idea: Add distilled water 1:1, 2:1, 3:1 to reduce FC < 10.
Concerns: Unclear what impact adding pH 7.0 to an existing pH solution is.
Idea: Use electronic pH monitor (or other non-Phenol red)
Concerns: Unknown accuracy overall, unknown if FC level impacts these.
Idea: Use Sodium thiosulfate (chlorine reducing agent) on pool water.
Concerns: Thought to impact phenol red test to an unknown degree.
Idea: as above - add Polyquat 60 to the pool bucket to increase chlorine demand and speed the process.
Concerns: Unknown impact on pH.
Idea: Set a bucket of pool water in sunlight to increase loss to sun - do not add bleach to this when increasing pool back to shock level. Measure pH once the FC has dropped below 10.
Concerns: May only be helpful if the pool is being covered during sunlight. Unclear if this will help in many cases - FC levels could be high enough that it will not drop quickly enough.
Anyone with critique and input please chime in.