How many times, or for how long, can we repeat CYA level within one test?

[Poolweekender]

Hi, being a recent TFP follower (addict is more like it ), my pool looks great, but I wonder if I am over-estimating my CYA level, as I have trouble, like many others, judging the CYA endpoint. I've read many posts with hints on how to determine the endpoint.

So...I've read many times that the test can be repeated "several" times by moving the water back and forth from the mixing bottle to the CYA measuring tube.
My question please - can the test be repeated for instance, for 30 mins or more, i.e., is it a chemical reaction between the reagent and the CYA that may dissipate, or is it simply a suspension, and if you are careful to mix thoroughly for 30 secs each time, can you repeat the test for, let's say, 30 mins or more?

i don't know if there is an answer to this, but being able to repeat this more than "several" times will b very helpful trying various lighting conditions when using the CYA standard.

Thanks!
Justin

 

[jblizzle]

I am not sure when the breakpoint is, but I do know the mixture will be impacted by waiting too long. I think within 10 minutes is likely reasonable, but would not suggest trusting it much longer.

There are a couple threads discussing this somewhere in the forum if you want to go searching

 

[Poolweekender]

Thanks Jason.

 

[kj5kb]

I've done 2-3 sometimes myself when it was questionable...but I remix and retry. Having a pint bottle of CYA reagent makes it easy...I've gone thru about half a pint in a year.