Balancing questions

[Cherylr]

Hello everyone,

I have some questions about my water chemistry.

Ordinarily I use bleach to sanitize my water; however, when school started back, I bought a bucket of tablets due to long late hours in my classroom. The water stayed clear, and I confess that I stopped testing it. We weren't swimming, and I was just waiting for a few free hours to close it. A friend is coming tomorrow to help close it, so I tested the water today. Wow! Ph was less than 6.8. TA was 10. FC was 3.

I've used the pool calculator and have been adding the recommended baking soda, borax, and bleach in small increments all day.

Ph is still less than 6.8, but I see a difference in the color, so I'm still adding Borax. TA is now up to 80. FC is at 15.

I checked CYA just now and oh my goodness. It was 90! I'm figuring it's those durn tablets, but I'm wondering if all the baking soda and borax might be suspended in the water and messing up my result?????

I'll check everything again in the morning. If the CYA is indeed correct, should I drain some now, or just wait until spring? Will this level damage anything over the winter?

Thanks for your help.

Cheryl
Kenton, TN
30' AG vinyl liner sand filter

 

[UnderWaterVanya]

Ph is still less than 6.8, but I see a difference in the color, so I'm still adding Borax. TA is now up to 80. FC is at 15.

I checked CYA just now and oh my goodness. It was 90! I'm figuring it's those durn tablets, but I'm wondering if all the baking soda and borax might be suspended in the water and messing up my result?????

The tablets are easy but deadly...think of them as the pool equivalent of an addictive drug - goes down easy but there are consequences!

I'll check everything again in the morning. If the CYA is indeed correct, should I drain some now, or just wait until spring? Will this level damage anything over the winter?

Up to you. Extra CYA isn't a problem over the winter... But in the spring you may have some extra work.

If you leave it at 90 you might want top dump in some polyquat as insurance...


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[chem geek]

For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm and it lowers TA by 7 ppm. So with 2 ppm FC per day usage, that's an increase in CYA of 36 ppm per month if there is no water dilution and a decrease in TA of 42 ppm per month. So getting to 90 ppm CYA is not that surprising. Trichlor is also very acidic. So it is not surprising that your pH and TA got so low.

 

[Cherylr]

Thanks for the information and advice. One more question: with a cya value of 90, do I need to bring my FC level to 35 or just add the polyquat 60? Current FC is 14. I got the pH and TA within normal range.