pH rising too quick?

[steveb21]

Last week my pH was 8.0, I reduced this down to 7.6.

Just test now and it's back up to 8.0. Weather has been on off here with a bit of rain on the majority of the 7 days between tests.

Is this normal?

 

[JVTrain]

What is your TA level? Higher TA levels lead to faster pH rise when the water is aerated (rain, splashing, turbulence).

 

[Demegrad9]

You'll need to fill in more detail here to make much assessment.

I see you're using a 2006C, have you tested recently and especially what's your TA? Is this a new pool? Do you have water falls or any other type of water feature?

What source of chlorine are you using?

 

[steveb21]

Not a new pool.
New-ish owner, completed a black water SLAM few months back.
Using liquid chlorine
No fountains

Tests results as follows

FC 6
CC 0.5
pH 8.0
TA 100
CH 300

 

[Richard320]

That doesn't sound extreme. When you lower pH next, target a lower number, like 7.2. It will reduce the TA faster and buy you more time between acid additions.

 

[JVTrain]

My TA is currently at 120 ppm and I've had to use about a gallon of acid in the last 2 weeks. I've had a minor leak I've been tracking down so in the last month, I've been adding a few thousand gallons of ~240 ppm TA water. TA was around 90-100 before I started my leak sleuthing, now, 120 and I've seen some significant pH rises when the pool was left uncovered during a long day of rain. The rain water itself is good for the pool because it has very little TA at all. However, the action of raindrops hitting the water surface is MASSIVE amounts of aeration, causing carbon dioxide outgassing. Like richard says, shoot for 7.2 pH next time around and this will also drop your TA a bit more. As your TA comes down, pH rise should also slow.

 

[steveb21]

Thanks all.

Lowered down to 7.2pH so will see how things go.

 

[steveb21]

So in about 10 days my pH has risen to 8.0 again... in these days we have had the odd heavy rain shower.

Is this a normal rise?

What exactly is pH minus? looking to purchase a bigger amount at this rate.

 

[JVTrain]

As far as normal, it's hard to say. Every pool is a little different. Dose it down to 7.2 again and then check your TA. If your TA has come down some, your pH rise will slow as well.

pH minus, as in the product name, is sodium bisulfate. Otherwise known as dry acid. It's not recommended for long term use in pools as it can lead to sulfate build up and deposits on your pool surface if used for long periods.

Muriatic acid aka hydrochloric acid is your best value and chemistry. It must be handled carefully in concentrated formulations, but it adds nothing you don't want in your pool.