Very low PH

Sep 19, 2012
3
Hi, my pool have a very low PH, i add PH + 3 times and still the same result, i bring a water sample to the pool store and the guy recommend to drain the pool and refill, did someone know what to do except the drain solution, hi have a well and it will takes 2 weeks to refill.
 
Christian said:
What is your chlorine level? If your chlorine level is high it can cause your pH to read low.

Hey Christian, did you mean read high? If it's a phenol red PH test, FC over 10ppm will cause the test to read falsely high.


To OP: As JamesW said...we need a full set of test results to really help you. Draining the pool can be avoided and is rarely advised unless there are other chemistry issues.
 
A couple things to keep in mind:
1) Anything below the lowest pH reading on the scale will read as that. So, despite calculating how much pH increaser you need to add, it may not be enough. You might be at 6.2 not 6.8 when you start. Which brings up
2) pH is a logarithmic value. It's not a straight line. One pound of soda ash may raise pH from 6.8 to 7.2, but it might only raise 6.2 to 6.4.

A full set of test results, preferably some you've taken yourself, with a drop test, not strips, would go a long, lomg way towards solving your problem.
 

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Christian said:
My mistake, I was under the impression that high chlorine could make the pH read incorrectly high or low. :oops:
The quote from Taylor's Pool & Spa Water Chemistry booklet on the issue of a high FC causing a false high pH reading is as follows:

FALSE READINGS: high levels of chlorine (usually > 10 ppm) will quickly and completely convert phenol red into another pH indicator (chlorphenol red). This new indicator is a dark purple when the water's pH is above 6.6. Unfortunately, some pool operators mistake the purple color for dark red and think the pool water is very alkaline and wrongly add acid to the pool.

When a sanitizer level is not extreme, only some of the phenol red may convert to chlorphenol red. However, purple + orange (for example, pH 7.4) = red. This error is more subtle as no purple color is observed and the operator does not suspect that a false high pH reading has been produced. Some operators neutralize the sanitizer first by adding a drop of chlorine neutralizer (i.e. sodium thiosulfate). However, thiosulfate solutions have a high pH and, if heavily used, may cause a false higher sample pH.
 
We need all the chemical levels in order to tell you what you need. Have the pool store run another sample for now and give us the following:

FC= Free Chlorine
TC= Total Chlorine
TA= Total Alkalinity
CH=Calcium Hardness
CYA= Cynaric Acid= Stabilizer
pH= Acidity/Alkalinity

For the pool store to recommend draining the water tells me that your CYA might be too high and the solution to fix that problem is draining. If the pool store could sell you chemicals to fix your water without draining, that would be in their best interest. It could be that they don't have a clue about how to fix it, and new water is their only suggestion.
 
In the mean time, it's time to read through pool school. The links have been provided, but the button on the upper right hand side of this page or the link in my sig will take you there We need information to help you. Size of pool, how you are testing, etc. Full set of test results please, below is a guide as to what we need to better help you

what-we-need-to-know-to-answer-your-questions-t10341.html
 
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