PoolDoc
06-11-2014, 12:04 PM
Phenol red is the indicator reagent used in all pool pH tests -- drops and strips. It's quite reliable, but it has a weakness: if the chlorine is too high, phenol red gets converted to a different indicator, chlorophenol red. With most phenol red drops, you can no longer trust the results one the chlorine gets above 5 ppm. Taylor's phenol red drops (in the K2006, the HTH 6-way and the K1000) have a compensating additive that makes them reliable up to 10 ppm.
The solution is simple: dilute with distilled water! For some complicated chemical reasons, you can dilute your sample 1:1 or even 1:2, without changing the pH enough to matter if you use distilled water. Tap water won't work; well water won't work, and normal bottled water won't work: only distilled or deionized water will work.
So how do you do it?
Just get a gallon of Walmart distilled water (http://pool9.net/distilled/) and a measuring cup. Add 1/4 cup of pool water, and then 1/4 cup of distilled water. If the chlorine level in your pool is really high, add 1/4 cup of pool water and then 1/2 cup of distilled water. Mix, and test your pH!
That's it!
The solution is simple: dilute with distilled water! For some complicated chemical reasons, you can dilute your sample 1:1 or even 1:2, without changing the pH enough to matter if you use distilled water. Tap water won't work; well water won't work, and normal bottled water won't work: only distilled or deionized water will work.
So how do you do it?
Just get a gallon of Walmart distilled water (http://pool9.net/distilled/) and a measuring cup. Add 1/4 cup of pool water, and then 1/4 cup of distilled water. If the chlorine level in your pool is really high, add 1/4 cup of pool water and then 1/2 cup of distilled water. Mix, and test your pH!
That's it!