CYA degradation in hot weather

[elaineinspain]

Is it possible to loose over 10ppm ( more closer to 20ppm) in one month?
I’m in the South of Spain. My pools water temperature has been around 30C or slightly higher for the past 3 months. I got my Taylor test kit on 13th July and immediately tested the cya, because I’d been relying on test strips before and we all know how inaccurate they are, but it’s the only thing they sell round here (I had to send off online for the Taylor kit and wait over 6 weeks for delivery from the States)
I followed the instructions here about testing - glance at the black dot, back to the sun, waist level, And got a reading of 70ppm. I checked with a friend if they also thought it was 70 by just glancing for the dot, and they agreed with me.
So I’ve been adding liquid chlorine 14% every day, and my pool is crystal clear. I’ve never had such sparkling, clear water!

Today I checked my cya levels and the black dot disappeared a hairs width under the 50ppm line.
I checked 3 or 4 times, and each time the same.
Is it possible to loose that much cya in 4 weeks?
My pool is in full sun 12 hours a day.
It’s used each day by 3 people at the most for 2 hours a day.
I’ve been keeping the chlorine levels at 7-8ppm (occasionally 9ppm)
The pH drifts upwards (7,8 -8) but I manage to get it down to 7,4 with muriatic acid once a week. My fill water has a high TA, hence my pool has TA 100 - 120. I’m guessing that is the reason my pH drifts up. But I’m not so concerned about TA. It’s my cya that has me perplexed…

Thanks in advance for your thoughts on this.
Elaine

 

[ajw22]

CYA - Further Reading

www.troublefreepool.com

How is CYA Lost and Degrade in Pool Water?​

In general, once you add CYA to pool water it will be in the water unless you drain the water that contains the CYA. Some CYA is lost as water splashes out from pools.

Water leaking from pools will take CYA with it. Unexplained dropping of CYA levels, especially if you have an auto-fill automatically adding fresh water to the pool, can indicate a water leak.

Evaporation of water from the surface of the pool will not cause a loss of CYA. The water will evaporate and the CYA will stay in the remaining water.

High pool water temperatures will cause the chlorine to oxidize Cyanuric Acid. This tends to show in water temperatures of 90+ degrees. Every 10F increase in temperature results in roughly doubling the rate of degradation.

Chlorine breakdown in sunlight causes CYA degradation by hydroxyl radicals. This can cause a loss from 2 ppm per month to 10 ppm per month depending on the amount of sunlight the pool is exposed to.

In an area with 90+ pool water temperatures and extreme sunlight exposure 10+ ppm of CYA a month can be lost through degradation.

 

[cledee]

Is it possible to loose over 10ppm ( more closer to 20ppm) in one month?
I’m in the South of Spain. My pools water temperature has been around 30C or slightly higher for the past 3 months. I got my Taylor test kit on 13th July and immediately tested the cya, because I’d been relying on test strips before and we all know how inaccurate they are, but it’s the only thing they sell round here (I had to send off online for the Taylor kit and wait over 6 weeks for delivery from the States)
I followed the instructions here about testing - glance at the black dot, back to the sun, waist level, And got a reading of 70ppm. I checked with a friend if they also thought it was 70 by just glancing for the dot, and they agreed with me.
So I’ve been adding liquid chlorine 14% every day, and my pool is crystal clear. I’ve never had such sparkling, clear water!

Today I checked my cya levels and the black dot disappeared a hairs width under the 50ppm line.
I checked 3 or 4 times, and each time the same.
Is it possible to loose that much cya in 4 weeks?
My pool is in full sun 12 hours a day.
It’s used each day by 3 people at the most for 2 hours a day.
I’ve been keeping the chlorine levels at 7-8ppm (occasionally 9ppm)
The pH drifts upwards (7,8 -8) but I manage to get it down to 7,4 with muriatic acid once a week. My fill water has a high TA, hence my pool has TA 100 - 120. I’m guessing that is the reason my pH drifts up. But I’m not so concerned about TA. It’s my cya that has me perplexed…

Thanks in advance for your thoughts on this.
Elaine

If the pool temperature is 90+ and you are getting lots of sun exposure, it's possible to lose 10ppm to 20ppm CYA per month.

 

[elaineinspain]

Aha!
So it’s the extreme sunlight and the warm pool temperatures!

Thanks so much for your replies.

I’ll just plan to check my cya levels once a month throughout the summer months.

Thanks again!

 

[elaineinspain]

If the pool temperature is 90+ and you are getting lots of sun exposure, it's possible to lose 10ppm to 20ppm CYA per month.

Thank you