ph increase

survey77777

LifeTime Supporter
Jul 18, 2007
85
0
ontario, canada
#1
Well here I am with yet another question.
My ph is up to at least 8.2 over a period of a week. I was away for a bit and had someone adding a little bleach each night for me, so I'm not sure when exactly it happened. pH was 7.4 when I left.
My alkalinity has dropped from 100 to 80 but over a more gradual period of time. My FC is at 5.
I've added some pH decreaser (something left over) tonight and I'll check it again in the morning but because I can't tell exactly what's in this product I'm not sure how much of a drop I should expect...trial and error 'til I move on to the muriatic acid. I guess I'm more interested in learning why this would happen.
Can anyone help me with this please?
Thanks
 

JasonLion

LifeTime Supporter
Platinum Supporter
TFP Expert
May 7, 2007
37,879
5
Silver Spring, MD
#2
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.
 

survey77777

LifeTime Supporter
Jul 18, 2007
85
0
ontario, canada
#3
Hardly any rain lately...very dry right now, no kids, no SWG, no waterfall/spa or fancy things I dream of owning ;) No plaster and no reason for there to have been much dust. My returns do aerate a little I guess, but they're not doing anything that they haven't been doing for the rest of the summer, so I guess it's still a mystery.
 

JasonLion

LifeTime Supporter
Platinum Supporter
TFP Expert
May 7, 2007
37,879
5
Silver Spring, MD
#4
There is only one more I can think of right now. If your FC level is above 10 the PH test can read higher than the actual PH. Other than that I'm stumped.
 

survey77777

LifeTime Supporter
Jul 18, 2007
85
0
ontario, canada
#5
Nope...if anything I had to panic for a moment when I got home and the level was lower than it should have been...when I took that reading the FC was actually at about 2.
I remain stumped too :?
Thanks or the suggestions though...I've learned something anyway.