Time to figure out pool water chemistry (and more)


Well-known member
Aug 14, 2018
Scottsdale, AZ
This is the safer way all the way around. Sure don't want someone showing up at your house asking about all of the water running down the road :shock: This also keeps your plaster protected.

You might need to do it a couple of times to get your numbers where they need to be.

For you CYA test do this for me:
-pull some pool water
-have some tap water ready
-put the same amount of pool water and tap water in a measuring cup. Maybe 1/4 cup of each. Mix it good
-now use the mixed tap/pool water for the CYA test.
-You will DOUBLE the number to find your CYA amount.

Doing the CYA test:
-GLANCE only!! Do not look for the dot. GLANCE in then look away.
-Pour to each line starting at 100. If you see the dot at a GLANCE then pour to the next line.

I will test that way if it's still really high! I am done filling/draining but did not have time to test the water yesterday. I did run my pump last night so hoping 40+ hours of draining/filling was enough to make a difference.


Well-known member
Aug 14, 2018
Scottsdale, AZ
Okay finally back in town and tested new water! Left a couple chlorine tablets in the floater while I was gone. Here are my new numbers:

FC= 9
CC= 0
CH= 875
TA= 200
CYA= 100
pH= 7.65

Any recommendations on what to do next? I bought some liquid bleach from Walmart the other day but have not done anything with it yet. Thanks for the advice to drain the pool. I think these numbers can be worked with (I hope!).
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TFP Guide
When you did the CYA test, was it the diluted test or all pool water? The CYA of 100 is still higher than we like to see for a non-SWG pool. But it can be managed. If you choose to keep it high, then the FC needs to be minimum of 7.5% of CYA. Aim for FC of 12ppm as your daily target. Over the summer, you may see CYA drop a bit, but it won't be fast. No more tabs though. Liquid chlorine only. Test FC and pH daily and add chlorine as needed.

If you decide not to drain more, you should drop the pH down to 7.2 or so. With that very high TA, the pH won't stay there for long. As you add muriatic acid to drop the pH, the TA will come down. As your TA comes down toward 100, you can start to allow higher pH.

The Pool Math app is a great way to help you figure out how much of each chemical to add. It also can help track your test results for you.


LifeTime Supporter
TFP Guide
Jun 12, 2011
To protect my plaster from the summer heat I used a lawn sprinkler to keep the pool surface wet while draining and refilling.


Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
Sebring, Florida
I would not try to maintain the pool with numbers like you post. You CYA is too high (which costs you MONEY trying (and most folks fail) to keep your FC up around 8-10 ppm.

Additionally, a CH of 875 invites Calcium scale into your pool.

I think you need a 50% drain to get both of those parameters in line. Please read (or re-read) "The "ABC's of Pool Water Chemistry" up in Pool School and you will see that those two parameters are outside our suggested ranges.

What is the cost of your fill water? What is the CH and TA of your fill water?
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