Very intriguing M!
Originally Posted by Hoppy
If the ppm in the water in equilibrium with the air above the water is a near constant percentage of the ppm in the air, this is an easy problem, but Murphy's Law seems to dictate that it isn't anywhere near a constant percentage.
Let's hope it's Henry's law, not Murphy's law that applies here!
My concern would be the speed of response... if the CO2 rises in the water, how fast will it equalize in the (non-moving) air space and turn off the solenoid?