mistergreen

The CO2 in carbonic acid will eventually break loose, in addition to the free CO2, as we all know the pH in CO2 filled water will eventually rise left alone. It's the carbonic acid that affect the pH.

Gerald

OK thanks tiger - so you're saying the K value for CO2 includes all the dissolved forms: CO2 gas, carbonic acid, and bicarbonate, right? I guess that explains why its K is so much lower than other gases.

tiger15

Actually, I am not certain, but can only assume that K is derived from total dissolved CO2 that by definition includes free and ionized CO2. The two exist simultaneously and interchangeably. Free dissolved CO2 in equilibrium is not the same as CO2 mist created by artificially injection.

Ionized CO2 is carbonic acid. Carbonate and bicarbonate are dissolved salt of cations, not CO2. The only way to ascertain what is included in K is to review the lab procedure that derived K.

The reason CO2 has much lower K than other atmospheric gases is that it is a polar molecule that has great affinity for polar H2O, and can ionize. O2 and N2 are non-polar and dissolve in free phase only, no comparison.

mistergreen

I'm finally back in the CO2 game after these many years. I plugged in this contraption into my 75G.
It doesn't look good. The bubble rate is less that 1/sec for the CO2 to dissolve or the the CO2 will overflow out the chamber. The amount of CO2 in the 75G is only around 3ppm. Going back to the regular PVC reactor.