Testing CH

[lapurple]

I can't seem to get an accurate reading for the calcium hardness. I keep seeing purple!

Tne first time I ignored the purple and counted drops till it turned blue. That gave me a reading of 525!

Then I tried the distilled water suggestion and only got 18.

What am I doing wrong? Could my well water have anything to do with it?

 

[mknauss]

Pool School - Calcium Hardness
The sample may turn purple during the test, or go to blue for a moment and then turn back to red/pink. This is called a "fading endpoint" and is caused by interference from metal ions. If this happens, do the test again, but this time add five drops of R-0012 before adding any R-0010 or R-0011L. Remember to count the initial five drops in the total.

Are you using any Cal-Hypo 'shock'?

 

[lapurple]

I did do the retesting that it suggested. It just turned purple before it turned to blue between drops. It never turned back to pink.

No I'm not using cal hypo. I am using sodium hypochlorite

 

[mknauss]

I have high CH and doing the 'fading endpoint' method works. So I suspect your CH is 525. Must be from the well.

Have you tested the well water for CH?

 

[lapurple]

I haven't tested the well water. I have some copper staining so I was thinking about testing the well water as well as the pool. Need to find some way to do that. Are there reliable test strips?