Yes, thanks for that input Mr. Smith. I do have to ask, what resultant traits did you notice that led you to the conclusion regarding the higher pH? I would have figured that the method did not matter so much as the medium used. A totally inert medium should not change the pH like reactive mixture (soil). You do have the experience, but I would like to know how you came to that finding. Intuition?
I decided to put an air stone in my rez but not sure if it was really needed. It runs for 30 minutes just before each flood. I figured that I would get the maximum oxygenation and minimize the acidification factor in bubbling CO2. You are probably well aware of this but for those that don't, CO2 bubbled through water will react to form a weak solution of carbonic acid lowering the pH by a bit.