PH climbing daily by .3

[SunMan]

Still fairly new to pool school, but my water is brilliant and I no longer am dealing with the idiots at the pool store :lol: My concern is that my PH is climbing daily by .3ppm, so every 3 days I'm adding about a quart of 31% muriatic acid. I daily replenish my chlorine with about 20-28 oz of liquid @12.5%. I would like to find a way to stabilize the PH. Any thoughts?
BTW, over the past 30 days my CA has gone from 50-60.
Test results:
FC 6
PH 7.8
TA 80
CH 300
CYA 60
CC 0
Salt 1825 for feel

 

[jblizzle]

Do you have any aeration like a waterfall, spill-over, etc? That can drive the pH up.

The way to slow the rise is to lower the TA. This can eiterh be done passively by keeping the pH in range and the TA will slowly drop, or more aggressively following the article in Pool School.

 

[SunMan]

I have a 2' high waterfall which is seldom used and there is a spillover from the spa with only a 1"drop. So now I am confused because the pool calculator tells me to aerate to lower my TA (which I thought was fine to start with since it is in the suggested 70-90+ range).

 

[JohnN]

Lowering TA is a process. You add Muriatic Acid to lower the pH and TA, and then aerate to raise the pH back up. You repeat the process until your TA is at the desired level. Aerating, by itself, doesn't lower TA at all.

 

[linen]

Do you run your deck jets a lot? They will raise ph very quickly.

 

[SunMan]

No to the deck jets. Seldom even use the pool except on weekends. Did get the TA down from 140 at refill 30 days ago. I'll just keep working on lowering the TA. Any ideas where the raise in CYA came from? Muriatic acid perhaps?

 

[JasonLion]

CYA only goes up when you add products which contain CYA, typically trichlor tablets, or granular dichlor. Muriatic acid does not contain any CYA.

 

[linen]

When you add cya by using granular stabilizer, it can take up to a week to show up in tests after it disappears into the water.

 

[SunMan]

The only thing I have put in my pool since I started reading this forum is liquid chlorine, salt and muriatic acid. So the CYA remains a mystery.

 

[257WbyMag]

CYA readings increasing by 10 without the addition of any CYA during that time is testing variance. That's all it is.

Your plaster is less than a year old, right? It is still curing and therefore, your acid demand will continue to be high. You can lower your TA somewhat, but you will still need to add acid fairly frequently and in good amounts because you have new plaster.

 

[duraleigh]

So the CYA remains a mystery.

The margin of error in that test is easily 10 ppm. As said before, CYA only increases in your pool if you add it.

 

[SunMan]

Thanks Weatherby for the insight on the plaster cure. I also can accept the test variance for the cya being user error. I think I'll just hold my TA at the low end of the recommendation and wait out the PH rise with MA Thanks again to all who responded!