High CYA. How much to drain?

Jb48560 · 2025-05-14T23:24:13-0400

Received my TF kit this week and if I did the CYA test correct I’m around 100-110. I weaned off puck use this week and suspected it would be up there. Prior I used strips and it was approaching the maroon color indicative of high Cya. I’d like to start off managing the pool
with reasonable levels of liquid chlorine. How much should I drain and what precautions should I take ? In ground pool I believe finished with pebbletec. It’s 12212 gallons in capacity I live in southern Texas it’s been hot and relatively dry lately. Thought it may be best to drain / fill late at night because of the heat. Thanks in advice for any help. I have a submersible pump and some time this weekend to tackle the chore.

Jimrahbe · 2025-05-14T23:33:23-0400

jb,

In Texas, you need a CYA of about 50 in the middle of the summer.. So, I'd drain about 60 %..

Did you do the diluted test that you need to do when your CYA is 100 or over??? If not, your CYA could be well over 110..

Thanks,

Jim R.

Jb48560 · 2025-05-15T00:25:46-0400

Thank you I will do the test again to be accurate as possible. Must you do this in the sun as the video suggests? I did this test under incandescent lighting indoors in the evening.

PoolStored · 2025-05-15T00:53:28-0400

Jb48560 said:
Must you do this in the sun as the video suggests?

Light is important for turbidity tests. Not sure what video to which you are referring.

For CYA over 90, use this 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

Jb48560 · 2025-05-15T07:35:45-0400

PoolStored said:
Light is important for turbidity tests. Not sure what video to which you are referring.

For CYA over 90, use this 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

Thank you this article it is immensely helpful! I’ll give this another go as I made several missteps it seems in my teast. The video I am referring to is in the TF’s you tube channel. It’s not as detailed as the instructions you shared. Any tip for accessing tpool school resources? When I’m logged in to participate in the forum it does not allow me to access articles or links that you shared. If I log out all is well and I can go through this article and all the resources. I noticed this when I registered for this site again actually.

PoolStored · 2025-05-15T09:39:54-0400

Strange. If you are using PC, clear your browser cache.

Jb48560 · 2025-05-15T18:42:35-0400

PoolStored said:
Strange. If you are using PC, clear your browser cache.

Jimrahbe said:
jb,

In Texas, you need a CYA of about 50 in the middle of the summer.. So, I'd drain about 60 %..

Did you do the diluted test that you need to do when your CYA is 100 or over??? If not, your CYA could be well over 110..

Thanks,

Jim R.

Hey Jim !

I did the dilluted test as you recommended at 100 barley visible went to 90 to fully obscure the black dot ..so my calculations is 180 or 190 is my CYA reading would you change drain recommendations as far as the amount? Thanks for any help you can lend.

PoolStored · 2025-05-15T18:44:57-0400

Replace about 70% of the water. See no drain water exchange here:

Draining - Further Reading

www.troublefreepool.com

Jimrahbe · 2025-05-15T19:12:07-0400

jb,

You can try to drain just the right amount, or you can just drain the whole darn thing and start over... :mrgreen:

If this were my pool I'd drain most of it and then immediately refill it with new water. Yes, you will have to initially add about 30 ppm of CYA, but I do not see this as a major issue.

Thanks,

Jim R.