Reading CYA test

[mikefamig]

I am testing CYA using the Pentair test kit with the vial that has a visible dot that slides up and down in the test sample. The instructions say to mix the chemical with the water sample and wait between 30 seconds and two minutes to read the results.

My problem is that when I take a reading at 30 seconds the result is 30ppm and when I read it after a minute or two the result becomes 35ppm. Which reading is accurate?

Mike.

 

[jblizzle]

Well, the test is +/-10ppm so .... take your pick and be consistent.

 

[Holydoc]

Wow... I did not even know there was a Pentair test for CYA. I wonder how it compares to the Taylor test?

 

[pookiesunshine]

....My problem is that when I take a reading at 30 seconds the result is 30ppm and when I read it after a minute or two the result becomes 35ppm. Which reading is accurate?

Mike.

Are you shaking it again between readings? i agree w/jb to be consistent, but i would tend to take the higher reading as a measure of safety.

 

[pooldv]

I'd round it to 40 to be on the safe side. 1 more ppm of FC is cheap insurance against algae.

 

[mikefamig]

I agree with taking the higher reading which is what I've been doing up to now. It seems correct to wait until the chemical process levels off.

 

[mikefamig]

Are you shaking it again between readings? .

No, the sample just sits

 

[duraleigh]

Regardless of the method, there is no CYA test that will consistently read a difference of 5 ppm.

After letting the sample sit for 30 seconds, it is almost second nature to re-shake it as you pick it up to pour into the view tube.

I have never seen ANY amount of "re-settling" and have used the sample to perform 6-8 tests by pouring and re-pouring into the view tube.

That said, I think it is just a little reassuring to give it another shake. Disregard the 5 ppm difference.....the test is not that precise.