Cal Hypo and testing Ph.

[Octavarium]

I just opened the pool for the season. Father in law had given us some Cal Hypo shock left over from the pool they got rid of. I know, not the best idea to use it but just wanted to get rid of it.

Prior to shocking,
Ph=7.5
Alkalinity 65
CYA 70
FC 0
Calcium 80

I left the pool over night and checked the FC yesterday and it was 26, it's down to 19 now.

At which point can I start testing the Ph? I had read the Cal Hypo will only temporarily increase Ph and as the FC comes down, the Ph will come down with it? It's still reading sky high right now.

 

[Donldson]

Your calcium is low enough that using cal-hypo isn't a problem, at least not occasionally/temporarily. However, it is the FC that is causing the high pH reading, not the chlorine source. The test becomes progressively less reliable above 10 FC. Once you drop down to 10 your pH test will be accurate.

 

[Octavarium]

Alright, thanks. Just have to wait it out then!

 

[Octavarium]

Is there anything else that is affected by high FC's when testing? Like your alkalinity and CYA, should you wait until the FC is below 10 for those too?

 

[Donldson]

Nope, just the pH. Technically the TA test can be affected (the R-0007 is a chlorine neutralizer for this purpose) but it only affects the color of the test and not the results.

 

[Richard320]

Is there anything else that is affected by high FC's when testing? Like your alkalinity and CYA, should you wait until the FC is below 10 for those too?

Alkalinity may shift from green>pink to blue>yellow or some shade in between. It's the color shift you watch for, not the actual shade. CYA should be unaffected.