The part I'm not sure about is the diameter of the section that connects the surface area chambers. It would seem to restrict the exchange of gases.
I don't see how the chinese made glass styles for instance would be any good. A big funnel reducing down to a pinhole at the bend before opening back up for the ph solution chamber can't be effective.
I'm not positive about this, but I think that air will exchange gases very easily that it's not a problem. Meaning whatever level of CO2 is in the bottom chamber will quickly equalize with the rest of the trapped air, despite the small opening. Like I said, I'm not positive, but I thought I remember something like that from a science class along time ago.
The Chinese glass one works great for me. It changes about 4X faster than a DIY one I made..small amount of liquid, and volume, and a decent surface area-comparably. The small diameter at the top doesn't have an effect on the equilibrium speed. It's all about surface areas to liquid volume in the checker.
Awesomely simple idea to build a drop checker. I am a big DIY fan and I am going to give this a shot. It suddenly occurred to me that the hotels keep these small travel size shampoo and mouthwash bottles which seem to be in the perfect size range so I took home one of those from my official trips.
They are however plastic and I was wondering if this will effect the test solution or the test itself. I feel it should not since you are using plastic tubing anyway. Any thoughts?