CYA increase by 60 ppm in a week ??

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N

Newton

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Jun 24, 2008
7
Thanks to one of my friend - I'm now addicted to your site and keep learning everyday. My goal is to have my TFP by the end of our (short) summer, although my partner is getting more and more suspicious of my skills... Help me to prove her wrong!

Anyways... This is my first post. Went to the pool store to get water tested last week on June 26, since I had been neglecting my pool and got some of the green stuff. At that point, my CYA level - according to their test - was 40 ppm. They recommended adding pH+ ( I was at 6.4...) and to shock to get rid of the algae. Before doing so, I read the Defeating Algae and Shocking your Pool posts, which were really useful - thanks to their authors. So I shocked one big time with Cal-hypo 65% granulated chlorine(about 24 onces - as recommended by The Pool Calculator) and a second time (12 onces), then added the pH+. My friend lend me his K-2006 test kit to allow me to test my CYA today (July 2) and I got a reading of between 90-100 ppm, which according to some posts I read here is too high. Note that the pool is in direct sunlight until 5:00 pm (or is it 5:00 ppm? hahaha)

So....My question: is it possible that my CYA increased that much in a week without me adding any "stabilizer" or "conditioner"? Was one of the CYA readings inaccurate? With my friend's test kit, the "black dot" disappeared quite quickly, that's for sure....

Here are my other test results for today:

FC: 5.5-6
TA: 75-80
pH: 7.8
CYA: 90-100 (?)

Cheers, and sorry for potentially bad syntax, English is not my first language.

AG 24'x4' Vinyl; Hayward Turboflo Pump and sand filter
 
You added pH+ (sodium carbonate) and cal hypo. This combination will often cloud a pool. So will dead algae. The CYA test meaures the cloudiness of the water from the reaction of the reagent with the CYA in your water. Wait until your pool is clear and retest the CYA. I think you will find it did not rise (unless the first test was in error.)
 
Thanks. My water was cristal clear when I tested it, so probably the first test from the pool store was not good.... I'll test again tonight with the test kit.

If it's still at 90-100 ppm, should I consider draining some of the water, or can I try to manage with this level? It is still safe to swin in?

What's the best advice you can give to avoid having my CYA increase further? I guess I need to avoid cal-hypo to chlorinate and start using bleach, right?

Cheers
 
If you are using cal hypo then that will not increase CYA but it will increase calcium hardness. Howver, dichlor is also sold as a granular chorinating compound and that will make CYA rise quickly. Make sure that you are using calcium hypochlorite and not dichlor.
 
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