Tested pool first time, strange CYA reading

colini

New member
Aug 4, 2020
2
Austin, TX
Hi all,

I've recently become the owner of an in-ground plaster pool. It's probably 8 years old. After reading things on this site, I bought a K-2006 test kit.

The pool guy is coming by weekly and the pool is in good shape. Today I did all the K-2006 tests and got these results:
FC - 2..4
CC - 0 (or very close to 0)
pH - 7.2
TA - 90
CH - 900 (maybe higher?)
CYA - see below

For the CYA test, when looking at the black dot from above, it disappeared long before the sample even reached the lowest mark (100). I followed the instructions carefully, so I'm as confident as I can be that it was done correctly.

Does this mean the CYA is very high? Is there another way I could test it?

Thanks,
Colin

edit: fix pH reading
 
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tim5055

Mod Squad
TFP Expert
LifeTime Supporter
May 11, 2014
11,038
Franklin, NC
Welcome!!

I hope you transposed the numbers and your pH is 7.2

Yes, your CYA test is showing very high CYA. This is not uncommon for a pool that someone takes over and the previous owner fed it a diet of 3" tabs all the time.


100 is the limit of the CYA test, so you have to do a diluted test. While the full instructions are in the Pool School, here is the short version. Mix 50% pool water with 50% tap water. Use this mixed sample as your test water. If still at a 100 you will need to dilute more. The problem is that when doing a diluted test not only do you multiply the rage of the test you multiply the error rate of the test, so results are a ballpark - not an absolute. Here is a great chart by JamesW to explain dilution rates and what you multiply the results by to get an approximation of your CYA level.

Pool water......Tap or distilled water.........Multiply result by

....1...................1................................2
....1...................2................................3
....1...................4................................5

The pool guy coming by weekly is why the CYA is high. Time to take over for yourself.



ow much Pool School have you read? Start with these:










 
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