Has Liquidator use increased your pH?

[Water_man]

smuggs raised this issue today in this thread and I wonder if other people noticed it as well.
Before installing my LQ my pH was as steady as a rock at 7.5 for 3 weeks. I used to add bleach manually.
After the newly installed LQ ran for 4 days pH increased to 7.7. Is this a coincidence?
I don't see how the Liquidator can cause pH increase but facts come first before theory.
I still have air leaking through the flow meter fittings. This will be taken care of soon once my Tygon tubing arrives. Maybe the air leak is related.

(CYA = 60, alk = 140)

 

[frustratedpoolmom]

if the air leak is adding aeration to your water, with an alk of 140 that could surely raise your ph.

 

[revstriker]

I have noticed an increase in PH as well. Before, I was adding bleach daily, and really only needed to add Muratic Acid maybe once a week. Now, I have to add MA about every other day.

As for air leaks, I don't have any that I am aware of.

 

[duraleigh]

I still have air leaking through the flow meter fittings. This will be taken care of soon once my Tygon tubing arrives.

That leak is most likely caused by inadequate wraps of teflon tape between the flow meter body and the adapters. Unscrew the adapters and wrap about three turns of tape on them or a thin coat of pipe dope.

 

[joenj]

I have not seen an increase in the ph. Ph is 7.4 and ALK is 100.

Our pool is without any fountains, slides or other ways for areation of the water.

 

[Water_man]

if the air leak is adding aeration to your water, with an alk of 140 that could surely raise your ph.

If the aeration is strong enough to drive the CO2 out, then alk should drop, shouldn't it? But it doesn't.

 

[Water_man]

I still have air leaking through the flow meter fittings. This will be taken care of soon once my Tygon tubing arrives.

That leak is most likely caused by inadequate wraps of teflon tape between the flow meter body and the adapters. Unscrew the adapters and wrap about three turns of tape on them or a thin coat of pipe dope.

I an aware of that, Dave, and thank you for the reminder. Today, when my Tygon tubing finally arrives, I'll be doing my "Liquidator installation overhaul" - taking care of the flow meter leak, changing the tubing, and replacing the leaking saddle fitting by Hayward's.

 

[Water_man]

I have noticed an increase in PH as well. Before, I was adding bleach daily, and really only needed to add Muratic Acid maybe once a week. Now, I have to add MA about every other day.

As for air leaks, I don't have any that I am aware of.

Maybe we should run a poll. We need more stats in order to see if it's indeed related.

 

[Guest]

if the air leak is adding aeration to your water, with an alk of 140 that could surely raise your ph.

If the aeration is strong enough to drive the CO2 out, then alk should drop, shouldn't it? But it doesn't.

No, aeration does NOT lower TA. Adding acid to drop the pH lowers TA. Aeration causes pH to rise without affecting TA.

 

[Water_man]

No, aeration does NOT lower TA. Adding acid to drop the pH lowers TA. Aeration causes pH to rise without affecting TA.

It seems that we understand the carbonic acid system chemistry differently.
The way I understand it is as following:
At any given pH there's a system of chemical equilibria between carbonic acid (H2CO3) and water and CO2, carbonic acid and bicarbonate and H+, and between bicarbonate and carbonate and H+. All these equilibria affect each other. When one component is driven out of the water, the system will react in the direction which compensates for the change.
Aeration works because it drives the CO2 out. This lowers the concentration of carbonic acid, and as a result bicarbonate associates with H+ and thus pH rises.
However, since you had driven CO2 out, by definition you lowered your alkalinity.

So, if aeration has any effect, you will see a drop in carbonates and bicarbonates = a drop in alkalinity.

 

[Guest]

No, aeration does NOT lower TA. Adding acid to drop the pH lowers TA. Aeration causes pH to rise without affecting TA.

It seems that we understand the carbonic acid system chemistry differently.
The way I understand it is as following:
At any given pH there's a system of chemical equilibria between carbonic acid (H2CO3) and water and CO2, carbonic acid and bicarbonate and H+, and between bicarbonate and carbonate and H+. All these equilibria affect each other. When one component is driven out of the water, the system will react in the direction which compensates for the change.
Aeration works because it drives the CO2 out. This lowers the concentration of carbonic acid, and as a result bicarbonate associates with H+ and thus pH rises.
However, since you had driven CO2 out, by definition you lowered your alkalinity.

So, if aeration has any effect, you will see a drop in carbonates and bicarbonates = a drop in alkalinity.

Where your error comes from is that carbonate hardness (what we call total alkalinity) is only the measureable part of the buffer system by definition, which is the bicarbonates (there is actually very little carbonate ions at normal pool pH). When we test TA we are actually only testing the bicarbonate part of the buffer system (at normal pool pH). Once you convert the bicarbonates to carbonic acid, by definition you have lowered the carbonate hardness or total alkalinity. The net result is that you have also lowered the pH. NOW, the tricky part is how to raise the pH without affecting the carbonate alkalinity. If you just introduce OH ions by adding a base you WILL convert some of the carbonic acid into bicarbonate and produce water but you are not shifting the equalibirum point but if you aerate you are actually REMOVING some of the carbonic acid and actually shifting the equalibrium point. This is about a deep as I will get without moving this to the "deep end" and it already probably should be there.
If you would like to continue this in the "deep end" please start a thread there and PLEASE, in the future, let's try and keep any theoretical chemistry out of the general forum.

You might want to read ta-what-is-it-really-t4979.html to get a better idea of the chemistry. Even that is pretty basic because I wrote it so people without a chemistry background could get a handle on it if they tried.

 

[Water_man]

You might want to read ta-what-is-it-really-t4979.html to get a better idea of the chemistry. Even that is pretty basic because I wrote it so people without a chemistry background could get a handle on it if they tried.

As you suggested, my reply is here at The Deep End.