This is a continuation of this thread.
You're saying exactly what I'm saying : aeration removes the carbonic acid.
Actually it removes only one thing - carbon dioxide. The equilibria of the system do the rest of the job. The CO2 that you kicked out by aeration came from the HCO3-, hence you reduced your HCO3-, namely you reduced your alkalinity.
There are only three ways to reduce your alkalinity :
1. Dilution
2. Forming an insoluble salt with carbonate (for instance calcium carbonate.)
3. Getting read of CO2.
This is what aeration does. The process of doing it in the pool is lowering the pH first so that more carbonic acid is available and hence more free CO2 is dissolved in the water, but lowering the pH per se doesn't lower the alkalinity because the CO2 is still there .
If you still think I'm wrong, please show me how can aeration increase the pH without removing CO2 out, and how removing CO2 out doesn't effect alkalinity.
If you can do that, then you'll disprove the law of conservation of matter.
waterbear said: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.
You're saying exactly what I'm saying : aeration removes the carbonic acid.
Actually it removes only one thing - carbon dioxide. The equilibria of the system do the rest of the job. The CO2 that you kicked out by aeration came from the HCO3-, hence you reduced your HCO3-, namely you reduced your alkalinity.
There are only three ways to reduce your alkalinity :
1. Dilution
2. Forming an insoluble salt with carbonate (for instance calcium carbonate.)
3. Getting read of CO2.
This is what aeration does. The process of doing it in the pool is lowering the pH first so that more carbonic acid is available and hence more free CO2 is dissolved in the water, but lowering the pH per se doesn't lower the alkalinity because the CO2 is still there .
If you still think I'm wrong, please show me how can aeration increase the pH without removing CO2 out, and how removing CO2 out doesn't effect alkalinity.
If you can do that, then you'll disprove the law of conservation of matter.