Ph rapidly changing?

[Fletch03]

So I got home from work today and waited for the sun to go down and tested chemicals. I have a 3 week old plaster pool that is in the sun all day so I have been constantly adding chlorine every day. Here is my first test:

FC: 0
Cc: .5
Ph: 7.0
Ta: 130
Ch: 300
Cya: below 30 probably around 20. New pool and slowly raising this. Will add more stabilizer on Sunday


So I add about 64 oz of bleach per the pool calculator to get chlorine up to 5 and that is it. I retest an hour later and here are the results:

FC: 6
Cc: .5
Ph: 8
Ta: 130
Ch: 300

So why would my ph fluctuate so much in about an hour? Same thing happened between last night and this morning. Went from 7.2 last night to about 8 this morning so I added a little acid this morning. I know new plaster raises ph but I can't imagine a quick change like that. Any reason why this would happen? I went ahead and added a little acid after the second test and will retest in the morning.

Also for some reason my Ta is a little high. I have been trying to knock it down by keeping ph low. Is 130 too high or should I just not worry about it and wait for a rain or the eventual top off of the pool due to evaporation?

Thanks for the help

 

[257WbyMag]

Your pH changes rapidly because you have new plaster and it's curing. This process will take at least a year so expect to need to add lots of acid over these next 12 months. You can lower TA somewhat. That will help. It won't change the fact though that as long as your plaster is curing, the pH will constantly be rising.

 

[Fletch03]

So in one hour it would raise that much? I did forget to mention that I brushed the pool after the first test. Maybe this did it?

 

[257WbyMag]

So in one hour it would raise that much?

Yep!