CYA off the chart high

Wadelaw

New member
May 30, 2020
3
Orlando, Florida
Pool test results from this morning:
Free Chlorine: 28
pH: 7.0
Total Alkalinity: 80
Calcium Hardness: 430
CYA: 200
Water Temp: 85°
(Taylor K-2006 test kit)

Pool specs:
Orlando, Florida
10,000 gal in-ground
Plaster
Chlorine
Variable Speed Pump with pressure gauge

My pool calculator reports the following:
Free Chlorine is a bit high
pH is a bit low
Alkalinity and Hardness OK
CYA is off the chart high

My research suggests I need to drain/replace water from the pool to lower the excessively high CYA. After that is done, re-test, add appropriate chems, re-test after water has exchanged one time, repeat.

Are my conclusions correct? What are my next steps? What order do I do these things?
 

Wadelaw

New member
May 30, 2020
3
Orlando, Florida
Welcome to the forum!
Can we assume you followed the dilute test for that CYA result?
You will need to drain and refill. The method depends on your risk acceptance and if you have a shallow water table in your area. This is a good read on draining -- Draining - Further Reading
I suggest you read ABC's of Pool Water Chemistry.
Yes, I had to do the dilute test. Thank you for the confirmation if what I assumed. After the water has been replaced, in what order should I test/adjust? FC first? TA first? Then what?
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
32,995
Laughlin, NV
Once you have drained/exchanged, run the pump for a couple hours and brush. Run a full set of tests. Then add chlorine, CYA if necessary, and adjust pH, if necessary. Once that has levels all in range, then adjust CH if necessary. TA will be managed by keeping your pH in the 7's.