CYA questions

[BIG R]

I am the proud owner of 2 pools. The 16000 gal inground vinyl in Iowa which obviously has to be winterized. About 30% of the water is removed in the fall and replaced with fresh water in the spring. Each spring I add 1 to 2 gallons of stabilizer to achieve 30 to 40 ppm cya. 4 3" tabs per week in the chlorinator and 2 gal liquid shock per week. Ph and TAdrift to the low side occasionally and must be adjusted. CYA stays 30 to 50 ppm.
The 16000 gal inground pebble tech pool in Oro Valley (Tucson) Az. is bydifferent. I have come to the conclusion I can not get an accurate CYA reading for this pool. The ph raises over time and with that the CYA reading also increases. Ph does not affect actual CYA levels, but seems to affect the concentration analysis. When ph is 7.2 to 7.4, CYA is 40 to 50 ppm. If ph is 8.0 or above, CYA is 80 to 90 ppm. I try to monitor the pool water for signs of high CYA concentration such as chlorine lock. If evident I will drain and re fill with fresh water. Costs about $100. I use both


Taylor K2005 test kit and aqua check 7 way strips.

 

[PoolStored]

Can you post a full set of test results? FC, CC, pH, TA, CH, CYA.

Use this link and start at #8

CYA - Cyanuric Acid Test

Cyanuric acid (CYA) is the chemical name for the product commonly called “pool water stabilizer” … Read more…

www.troublefreepool.com

 

[TinFoilHat]

I use both Taylor K2005 test kit and aqua check 7 way strips.

You need proper test kits in both locations. A K2006C or a TF100.
Test Kits Compared

 

[BIG R]

The only difference i see in the 2 kits is FAS DPD Chlorine test. I have all the current reagents. I don't have issues with chlorine residual

 

[Newdude]

The only difference i see in the 2 kits is FAS DPD Chlorine test.

Yes. That one is super important in another discussion but not this one. Post the full test results from the k2005. The strips are far too vague for most tests, even if they had any accuracy.

 

[BIG R]

K2005 Test Results:
Ph 7.4
TC 3
FC 2
CC 1
Hardness 150
TA 80
CYA 40
Added 3" tablet to chlorinator

 

[TinFoilHat]

FC is too low and CC of 1 might mean algae. You can add some liquid chlorine to get your FC up to about 6 ppm and then run an OCLT starting after sunset. Run the pump overnight without a SWG running and then test the FC again before sunrise to see if the FC number has changed. If you lose FC overnight then you have algae and you need to SLAM. Also, add the deets of your pool and equipment to your signature.
Overnight Chlorine Loss Test
SLAM Process
FC/CYA Levels

 

[BIG R]

Thanks for the input. I'll keep an eye on it