Ph problem with New Plaster

[tommykat]

This is my first post. Great site!. I've been following it for two months and I really like it.
I had my pool replastered (1st time on a 21 year old pool) on May 24. The plaster contractor gave me start up procedures from the National Plasterers Council - 2 pages with the "NPC" logo in the background in large blue letters. I believe I've seen it on this site.
The procedures say to adjust the ph to 7.2-7.6. My readings using a TF-100 kit are: ph 8.2, TA 80, CH 225, FC 1. On day 1 (May 25)
I put in acid three times - 28, 40 and 40 oz. per the pool calculator on TFP. My acid is old- at least 4 or 5 years. Today (May 26) the ph is still 8.2 and maybe higher since the test kit only goes to 8.2. Should I get new acid and try again or is something else going on?
Thanks for your help!

 

[Richard320]

Welcome!

If the dosages poolmath kicked out went up each time, that means the TA went up, which is common in new plaster. Assuming it's muriatic acid you're using and it still smokes a little and irritates your eyes and lungs when the wind shifts like it always does, it's probably still good and things are normal. At the rate you're going through it, you'll be needing to buy more acid soon anyway.

 

[woodyp]

At that rate of application, what you have won't last long anyhow. Use PoolMath to see what effect those additions SHOULD be making, test again in 30 minutes and adjust your results. What you have is probably just fine though. What Baume are you using? Welcome to the forum.

 

[tommykat]

At that rate of application, what you have won't last long anyhow. Use PoolMath to see what effect those additions SHOULD be making, test again in 30 minutes and adjust your results. What you have is probably just fine though. What Baume are you using? Welcome to the forum.

20 Baume/31.45%. So I should keep testing and adding acid every hour or so until the ph comes down? A whiff of my acid is irritating, so it is probably ok.
Thanks again.

 

[tommykat]

Welcome!

If the dosages poolmath kicked out went up each time, that means the TA went up, which is common in new plaster. Assuming it's muriatic acid you're using and it still smokes a little and irritates your eyes and lungs when the wind shifts like it always does, it's probably still good and things are normal. At the rate you're going through it, you'll be needing to buy more acid soon anyway.

Dosages went up because on the first dose I was attempting to lower ph to 7.4. On the next two I was trying to lower ph to 7.2. Each time when I checked later the ph was still at 8.2. It was like the acid I put in had no effect. I have not seen a ph reading lower the 8.2 yet. Also, the TA has not increased. When I filled the pool up (Houston public water) and checked the TA it was 90. I then added Jack's Blue Stuff as the sequestering agent. TA was 80-90 when checked later that day. Today when I checked the TA first thing it was 80.
So, this afternoon I went and bought new acid and added 19 oz per Poolmath to try and lower the ph to 7.6. I will see if this helps.
Thanks

 

[Divin Dave]

Tommykat,
The test kit can only test up to the 8.2 mark. It cannot test for higher than that. And so if the test says it's 8.2 does not mean thats what the pH actually is. Your PH was way above 8.2. Thats why you didnt see a change in the PH test yet

Once you get enough MA in there to drop the pH to a testable level, you will definitely see it change and be able then to zoom in it.

Couple days ago someone else expereinced the same thing. They had to put in more than a gallon to get the pH down