pH of 16.9??

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skurys

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Apr 25, 2012
31
So I wanted to confirm my ph test, which kept turning pink despite low chlorine levels. The pool store also got 8.2+ (higher than their chart) and did some "acid demand test" and the lady said it gave an "adjusted ph" level of 16.9!

Just wondering if that is even possible, and does that mean I will need to put in 61 L of muriatic acid to correct this?!?

Funny thing is the pool was almost clear april 16th, and the ph was 7.4 as per the pool store. Only thing used since was some cal hypo for a few days, and bleach since then. Here is what the store's tests read:

FC 3
ph 8.2
acid demand 19 drops
adjusted ph 16.9
TA 80
CYA 0
CH 120

Any suggestions greatly appreciated, Thanks!
 
skurys said:
Oh also, is there a special way to add the muriatic acid..? The bottle says to turn off the pump for 12 hours...
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maybe if you are trying to acid wash your pool. You want it to mix in so add the acid in front of a return. Here is a link from pool school

pool-school/recommended_pool_chemicals

Also regarding pH, 16.9 is suspicious. Typically pH is only reliably measured to 14. if that were the case it would be extremely toxic and would cause severe burns.

Maybe get a tf100 test kit and measure it yourself.
 
Yeah she said its not an actual ph 16.9 but adjusted... (tho even she wasn't sure what that means exactly) I just tried with a ph test with chlorine neutralizer and still gives pink, so its something above 8...

I put in 500ml and I guess I'll see what it reads tomorrow...
 
Maybe someone could explain what the acid demand test is in relation to the ph, this is the test she did to come to that value. She added drops until the solution changed and that gave her 16.9
 
I'm sure someone can expound upon that "adjusted" garbage, but we never worry about anything other than actual pH. I think the acid demand test is supposed to give some indicator of how much acid will be needed to reach some arbitrary level, but IMHO it only contributes further points of testing errors and confusion.

Do yourself a favor - take the "real" pH level, plug it into the PoolCalculator and find out what is needed to reach your target level.
 

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Unfortunately I'm in Canada and don't have the 150$ for the big kits that I can have shipped here.

But I assumed 8.2 as thats the highest on my ph test, and treated for that, then checked again and added a big more.... now it's starting to come into range yay!
 
Yakiman said:
Not a rocket scientist, but isn't pH by definition 0-14?
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not by definition, it is a log function of the concentration of free hydrogen. Theoretically it can be as high as you want, but practically it is extremely difficult to measure above 14.
 
skurys said:
Unfortunately I'm in Canada and don't have the 150$ for the big kits that I can have shipped here.

But I assumed 8.2 as thats the highest on my ph test, and treated for that, then checked again and added a big more.... now it's starting to come into range yay!
Click to expand...

The acid demand test is useful for determining how much acid you need, but the calculation of a pH based on that doesnt sound quite right.

I like it because apparently my test only goes to 8 (taylor 2006) so the acid demand gives me a better idea of how much acid Im going to need. Am I just barely over 8 or am I waaay over 8.
 
It depends on the size of the pool. Each drop for the acid demand test is approx 16-17 ounces of 20 baum acid in my pool. For example if my pool ph is 7.8 and it takes 2 drops to lower it to 7.5 for my pool its approx 32 ounces pool caculator comes up with 35. Its in the ball park. Pool calculator is your friend
 
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