Why does my PH keep going up?

Jul 4, 2007
7
#1
I have a one yr old 10,000 gal in ground Gunite pool, water temp is 77 degrees. I test chlorine and PH daily, my PH goes up about .2ppm-.4ppm daily, my TA seems to go down quickly, but not as fast as the PH changes. My chlorine is always stable, I add about 10oz daily. Can someone tell me why my PH might be going up so much. I know having a new pool can cause this, but the pool is a year old and the PH doesn't seem to be slowing down at all.


Any answers welcomed.

Thanks
 

JasonLion

TFP Expert
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May 7, 2007
37,879
Silver Spring, MD
#2
PH goes up for two reasons. If your plaster is less than one year old the plaster is still curing. As the plaster cures it raises the PH. Also, the combination of high TA and aeration will raise PH. If you post a full set of test results we might be able to suggest some adjustments that will slow or eliminate the PH increase.
 
Jul 4, 2007
7
#3
My pool was finished about 13 months ago. My test numbers from the last few days are:

FC 4
PH 7.8
TA 90
CH 280
CYA 40

I added 24 oz. of MA to drop it to 7.2, because it goes up so rapidly. Maybe I am dropping it too much? Anyway,
my numbers for the following day were:

FC 3
PH 7.6
TA 80

I added 19 oz. of MA. The following day the PH was up to 7.9 and the TA was down to 70. I added 24 oz. of MA and added 50 oz. of baking soda?

Maybe this is normal. I just feel like my PH and TA, but especially my PH, is moving around alot. :?

Thanks.
 

Butterfly

TFP Expert
LifeTime Supporter
May 31, 2007
10,045
South Carolina
#4
Hi rw,

Here is a portion of a post I found that may have more items for you to consider............(I copied/pasted this partial post months ago, and apologize that I am unable to credit the author. However, it is one of the TFP gurus.)

"PH can go up for a number of reasons. The most common is CO2 outgassing caused by aeration of the pool (rain, kids playing, SWG, waterfall, spa, etc). Blown in dust can sometimes be fairly basic, raising the PH. New plaster will raise the PH for several months to a year.

If you compensate for PH increases from CO2 outgassing by adding acid reguarly, the TA will go down over time."


If you add all your pool and equipment info in your signature, it would be helpful.

What test kit are you using?

Do you have water features, bubblers, etc?
 

JasonLion

TFP Expert
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May 7, 2007
37,879
Silver Spring, MD
#5
You should allow TA to fall to around 60 (or even 50 if you don't have an SWG).

If you have a SWG, I suggest that you raise CYA to between 60 and 80.

That should greatly reduce the rate of PH increase, particularly when the PH is around 7.6 to 7.8.
 
Jul 4, 2007
7
#6
To answer jj, I use a Taylor K2005 kit. We have a 10K gallon IG, gunite pool. Cartridge filter and one water decent. I have kept it off for the past two weeks to see if that was causing my PH to rise. It hasn't seemed to make a difference.

In response to JasonLion, I don't have an SWG so you are saying that it is ok to let my TA drop to 60? I have never let it drop that low before.

Thank you both for your input.

rw
 

JasonLion

TFP Expert
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May 7, 2007
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Silver Spring, MD
#7
Yes, as long as you are using bleach for chlorine and have CYA around 40 you should be fine with TA down around 60, perhaps even just a little lower. It is crucial to have a higher TA level when using trichlor tablets, which most people use, so that is why much higher numbers get quoted most places.

The rate of PH increase is higher when TA is higher and when PH is lower. Lowering TA and letting pH go up just a little will slow, or perhaps stop, the rate of PH increase significantly.
 

cruzmisl

Well-known member
May 26, 2007
185
#8
JasonLion said:
Yes, as long as you are using bleach for chlorine and have CYA around 40 you should be fine with TA down around 60, perhaps even just a little lower. It is crucial to have a higher TA level when using trichlor tablets, which most people use, so that is why much higher numbers get quoted most places.

The rate of PH increase is higher when TA is higher and when PH is lower. Lowering TA and letting pH go up just a little will slow, or perhaps stop, the rate of PH increase significantly.
This is interesting. I use liquid chlorine purchased from my pool store (it's cheaper than bleach in my area) and pour it in my Liquidator. I too have pH rise but not as bad as the OP. I usually keep my TA around 100. I'm going to try it at 60 and see what happens. I have a vinyl pool liner so it should be fine.