Ph OF THE POOL WATER

[JIMMICCO]

Asking for some ideas.

We have a concrete salt water pool; the ph normally tests above 8.2 and while i can adjust it to the 7.2-7.5 range with muriatic acid, the adjustment is short lived. Within 2-3 days it has climbed back up again. Other test results using the t-100 kit are: Chlorine 3-4 ppm, ca-275, cya-60-65, total alk -180.

So i have 2 questions: Why does the ph keep rising? Should i use some other acid to try lowering the ph?

Thanks.

 

[tim5055]

Welcome to TFP!

A little more description on your pool would help. Age, equipment, waterfalls, things like that.

pH rise is caused by curing plaster and aeration caused by water movement. A busy waterfall or a newer plaster pool could be the cause.

 

[Divin Dave]

Hi Jimmicco,

your pH keeps rising because your TA of 180 is way too high.
If your plaster is new, then curing of the plaster can also add to it.
The TA controls the rate of how fast pH rises. Lowering it to within TFP recommended levels will help slow it down.
Pool School - Recommended Levels

Muriatic Acid is the best chemical to lower the pH.

Here is how to lower TA
How to lower TA

 

[duraleigh]

Welcome to the forum.

As you read more and more on the forum. You will find that almost ALL pools have a tendency for rising pH and Salt pools are especially prone to that.

That said, if you lower your TA, you will find your pH will probably become much more manageable.

Lowering TA is done with acid AND AERATION, It is a process that may take a few days but will be worth it. There is an article in Pool School that will explain the process and we'll help if your have question.

read "The ABC's of Pool Water Chemistry" up in Pool School before you start the TA process.......it'll help with the basics you need.

Muriatic acid is the single best way to control your pH, incidentally........don't use anything else.

 

[JIMMICCO]

The pool was installed in 2006 and holds approximately 13,500 gallons. There are 4 return jets in each corner of the pool. There are no waterfalls. One skimmer. Solar heated but that has been off for the summer

 

[chem geek]

It's mostly the high TA level then. The aeration from the saltwater chlorine generator combined with the high TA leads to pH rise. Also, if your piping from the SWG unit to the pool return is relatively short, then you can also have chlorine gas outgassing and should consider pointing the return a little down to give the chlorine more time to dissolve into the water. First though, I'd lower the TA significantly and see how that goes.

 

[BuckeyeChris]

lower pH with acid, aerate constantly to raise the pH up again so you can add more acid, more often.