CYA zero and not rising.

[cgarai]

Hi,

I'm having trouble with CYA at a zero level after the winter. I've added 5# and still see little or no change. I first added 3# and could detect an increase in cloudiness in the test tube. Then I added 2# more and tested 3 weeks later and it's clear again. I can't find a record of measuring CYA since 2015 at which point it was 30ppm.

Last December the FC was at around 11ppm. At that point I turned the pumps off. This pool is covered almost all of the time, so I placed a cover pump on it for the winter. The pool remained undisturbed until the beginning of April. At that point the water was clear, the FC was 2-3ppm, pH=8.2. I turned on the system, added 3l of acid and by the beginning of May the FC was at 5.5ppm, CC=0, pH- 7.5-7.7, CH=475, TA=100, CYA = 0 (totally clear). Due to the heavy rains in Northern Cal this winter I had some dilution. The salt concentration went from 3700 to 3400ppm. When the pool was opened for the first few times this spring it had a slightly fishy smell.

I've never had a problem with cloudiness in my pool. I typically shoot for a FC of 3-4ppm, on the assumption I had a CYA of 30ppm.

Any idea why my CYA will not shift? The latest measurement of CYA=0 was with FC=9ppm, pH=7.6, temp around 79F.

Thanks

Chris

 

[mknauss]

Curious. How are you testing the water? How old are the reagents you are using?

Take care.

 

[Pool Tool]

CYA of less than 20 can still show up as zero on the test. If you were at zero this spring then added 5# (18 ppm) you might still show zero on the test. I would add another 5# wait a week then retest. Obviously a sunny day, back to the sun, etc.

Good luck.

 

[cgarai]

I have a TF-100 test kit. I think it is 3 years old.

Thanks,
Chris

 

[mknauss]

If your pool holds FC, your salt did not drop appreciably over winter, then at least some of your CYA should be there. I would be careful how much you add.

Also - at 3 years - I would suggest getting a refill of your reagents. Especially if they were stored in a garage or outside shed. I store mine indoors - but our garage is nearly the temperature of the surface of the sun in summer!!

Take care.