CYA test idea

[DonQ]

Any thoughts on this? I have a lot of trouble with the CYA test, do I see the dot, or not. I get good results with a slight modification:

Prepare the test solution as usual, but before putting the drops of the mix into the tube, place the tube on the taylor stirrer with the light switched on, but no stirbar. In a semi-dark room (my kitchen with the lights off and the shade drawn works for me) continue the test as usual, looking straight down the tube from close range. As you get close, move the tube very slightly side to side if you are unsure when the dot disappears.

 

[jblizzle]

Nope ... having the light under the tube will make the test read way too low I think.

 

[anonapersona]

I do it as suggested, back to the sun. The first run I do by filling to each line and looking to see if the dot remains. Then I do a second run adding drops slowly until I get to the disappearing point. If that is the same, I stop, if not I do both again after returning the mix to the squirt bottle.

Just did my June "Full Test" of all parameters. Found my CYA at a low 30 where only 3 weeks ago it was 45 due to vacation use of tablets. Eyeing another vacation..... so hard to waste that "20 ppm window" of CYA opportunity!

 

[ComputerGuyInNOLA]

I had a hard time with this test in the beginning. I am sure you have seen those optical illusions where you stare at a dot on a piece of paper and when you look away you still see the dot. I do my test as outlined in the instructions here but I don't stare at the dot, I look at the white area surrounding it. It seems to make it easier to determine when the dot is no longer visible.

 

[Alan762]

"Found my CYA at a low 30 where only 3 weeks ago it was 45 due to vacation use of tablets." Did you drain your pool?

 

[anonapersona]

"Found my CYA at a low 30 where only 3 weeks ago it was 45 due to vacation use of tablets." Did you drain your pool?

Two possibilities. First we have had a lot of rain. I left a bucket outside recently and found a foot of water in it, and mosquitoes. The pool had been draining through the overflow, so essentially yes it was drained.

Plus I took the sample when the pool was not running. Silly me, I had noted a bit of excessive chlorine usage and assumed lack of brushing had let some algae start when FC was so low. But that sort of drop is right for lowered CYA level. Of course I was out of liquid chlorine so I used some cal-hypo as CH could be higher.