PH rise and acid additions....

[mknauss]

I see that as a 7.5. Does That make sense with your acid addition?

 

[DanF]

Thanks. It mostly does; I used Pool Math and started with a current pH of 8 and it said add 14 oz to get to 7.6. So...if my starting pH was really 7.9, the dosage lowered it by 0.4.

I'm still unsure why prior doses of similar quantities seemed to have no effect on my pH. One difference this time was I used a new bottle of MA (the other bottle in a 2 pack purchased about 6 months ago). However I've read many places that MA does not expire/deteriorate so not really sure...unless my pH was much higher than 8 when I started.

 

[mknauss]

MA does not age. So I suspect your pH was higher than 8. With the color comparator, you cannot read above or below the range it shows. When you measure the max, add acid to get to 7.6, circulate for 30 minutes or so, test again, add more acid as necessary until you get to your goal pH.

 

[DanF]

Thanks again Marty. I'm thinking my fill water pH must be pretty high, as I filled the pool on 3/30 after a pebble-tec repair. The water now is probably just getting into the testable range. I look into how high of a pH the electronic testers can test.

 

[mknauss]

I suspect you are using Colorado River water. pH of 8, TA 130ppm, CH 250 ppm. Test it some time.

 

[DanF]

I bet you're right on the Colorado River. My pool CH is about 230 right now 6 weeks after refill so 250 isn't too far off. But...if the fill water pH is higher than 8, I won't really know what it is with the comparator, correct?

 

[mknauss]

The fill water pH does not really drive pH rise in your pool water. TA and aeration do that.