Is my ph reading accurate?

[NickB23]

HI all,

I have high CYA (maybe 130-150) so I have been keeping my Chlorine level above 10ppm. The question is, is the high chlorine throwing off my ph reading? I have been trying to lower total alkalinity so I have been adding acid. I was a bit dismayed as PH was really high after I added liquid chlorine.

I then read a post on this forum about diluting pool water with distilled water 1:1 ratio if testing ph with chlorine above 10ppm. I did this on wednesday and found my ph to be lower than I expected so I aerated for a few hours.

the question is, do I need to use this distilled water dilution method again?

Date	FC	pH	TA	Action taken after test
9/15/2023 18:04​	10.5​	7.7 (if NOT using 1:1 distilled method)
9/14/2023 19:09​				brushed pool
9/13/2023 18:43​	11.5​	7.3 (used 1:1 distilled H2O method)​	90​
9/12/2023 18:50​	15​	7.8​	95​	+ 64 oz 31.45% muriatic acid
9/11/2023 18:10​	7.5​	7.7​	100​	+ 14 oz 31.45% muriatic acid + 183 oz bleach 10%
9/9/2023 12:12​	9​	7.6​	100​	+ 2 lbs 99% trichlor
9/8/2023 18:58​	9.5​	8​	110​
9/6/2023 18:15​	2​	7.9​	110​	+ 18 oz 31.45% muriatic acid + 3 lbs 73% Cal Hypo
9/5/2023 18:08​	4​	8.2​	110​	+ 30 oz 31.45% muriatic acid
TF Pro kit arrived! 9/1/2023 18:56​	6.5​	8.2​	120​
Leslies test... 8/26/2023 14:54​	9.36​	8.1​	87​
Leslies test... 8/24/2023 13:12​	5.53​	8.1​	70​	+ 8 lbs baking soda

 

[ajw22]

FC of 10.5 to 11.5 is not likely to bleach out your pH results.

Your tests with FC of 7.5 to 9 find your pH in the high 7s Which seem reasonable.

What is your CYA?

Why not keep your FC around 9?

 

[NickB23]

FC is well above 100 (highest my kit measures) maybe 130-150?

 

[Jimrahbe]

FC is well above 100 (highest my kit measures) maybe 130-150?

Nick,

I assume you mean your CYA is over 100..

Thanks,

Jim R.

 

[ajw22]

FC is well above 100 (highest my kit measures) maybe 130-150?

CYA > 90 dilution Test​

For CYA > 90ppm, repeat the test adjusting the procedure as follows:

1. Fill the mixing bottle to the lower mark (15 ml line) with pool water.
2. Continue filling the mixing bottle to the upper mark (30 ml line) with tap water.
3. Shake briefly to mix.
4. Pour off half of the contents of the mixing bottle, so it is again filled to the lower mark (15 ml line).
5. Continue the test normally from adding R-0013, but multiply the final result by two.

If you need to dilute the pool water further then apply these ratios:[7]

Pool water	Tap or distilled water	Multiply result by
1	1	2
1	2	3
1	4	5

Note that when doing a diluted test not only do you multiply the range of the test you multiply the error rate of the test, so results are a ballpark - not an absolute.

 

[NickB23]

Nick,

I assume you mean your CYA is over 100..

Thanks,

Jim R.

Yes I did mean CYA haha!