Can I let evaporation lower CYA

[StuartS]

Hello all,

Pool is crystal clear, and all numbers in range. TA is 74 because I want to add borates.

My problem is CYA at 91 ppm. Can I let that lower through evaporation and refill this summer, or should I do it all at once? I have trouble reading CYA with the K-2006, so I got that number from pool store.

Thanks in advance!
Stuart

 

[RadEngr70]

Unfortunately that won't work. Pure water evaporates off leaving the CYA behind.

Requires a drain (water takes CYA with it) and refill to lower the CYA level.

(Splash out helps, and CYA is broken down at a very slow level naturally - but I don't think either of those mechanisms will get you where you want to be)

 

[Mr Bruce]

1) No, unfortunately CYA doesn't go down with evaporation. You will need to drain/replace some water.

2) I trust whatever number you get close to with your K-2006 WAY more than that pool store number. What do you get when you do the CYA test?

 

[borjis]

Best to drain down and replace, but use the taylor kit results, not the pool stores, which is likely
not accurate.

Do the test in full sun, with your back to the sun, holding the test tube at waist level shaded
by your body. pour in solution then as you are doing that, and look away, then at the dot,
then away, then at the dot. repeat until you get the reading.

pour the solution back into the bottle if you are not sure and test again.

ooops mr bruce posted just before i did.

 

[Richard320]

CYA doesn't evaporate.

Rumor has it that it degrades about 3% per month, but that probably wouldn't even be detectable on a test. The way to lower it is by replacing water, either through splashout, backwashing, or intentional replacement.

Having dealt with a pool with superhigh CYA before, I can tell you that it's a lot easier to maintain with lower CYA. I'd trust your results for the CYA test before the store's. Play with it some. Fill to 100 and glance at it. Dot visible? Fill to 90. People have also looked at it and then looked away over and over to avoid having the image burned in. You can pour the sample back and forth many times.

If you do end up deciding to drain and refill, just do it once and be done. As long as you leave a foot of water in the pool the liner should stay put.

 

[jeffchap]

No, CYA does not evaporate. Hence the reason we are so cautious using products that add it.

However, this is the one reading that pool stores most frequently get wrong. So I wouldn't do anything based upon that. Tell us what happens when you try to read it yourself and we'll walk you through it.

 

[borjis]

haha Richard, eagerly anticipating your trademark photo of the bleach truck one of these days!
(always get a kick out of it)

 

[StuartS]

Thanks for all the input! I had done the test before and tried again yesterday. Did at around 4:00, and sun was pretty bright. I can't see the dot when the solution is half way between the bottom and 100! My son-in-law came up with the same results. That would mean it's super high. There are links where people talk about a diluted test, but I couldn't find the link to it. What should I do?

Thanks again!
Stuart

 

[domct203]

Thanks for all the input! I had done the test before and tried again yesterday. Did at around 4:00, and sun was pretty bright. I can't see the dot when the solution is half way between the bottom and 100! My son-in-law came up with the same results. That would mean it's super high. There are links where people talk about a diluted test, but I couldn't find the link to it. What should I do?

Thanks again!
Stuart

When all else fails .........

Pool School !!!!!

Pool School - Extended Test Kit Directions

 

[zea3]

Pool School - CYA
Go straight to number 8 for the dilution test.

 

[StuartS]

It looks like I'm at CYA one-stinking-eighty (180). Need to drain 3/4 of pool (72%) just to get to 50. Hopefully I'll find time in evenings early next week. Glad I waited to put in boric acid! This is probably why I fight algae on ladder every year even though I worked hard on chlorine and cleaning.

Thanks for all the help!
Stuart