Reactors, KH, PH, bufferring, was (Major help needed)

I added a second reactor to my tank yesterday evening and set the controller to allow the PH to drop as low as 6.8 that would be 81 ppm with my KH (17). My bubble rate at each of the reactors was around 3 bubbles per second. After six hours the PH was still at 7.2 . This morning it was still at 7.2 - I cranked the C02 up some more, turned off the small hob filter, put on my glass canopies (they fit pretty tight), after 3 hours with the lights out my PH is still 7.2. It looks to me that the CO2 is dissolving very well, I get a few super fine bubbles out of the bottom of the reactors but obviously most if it is dissolving. I'm counting the bubble rate at the reactors so C02 is getting to the reactors. The PH controller is accurate -I tested the calibration last night and a PH test kit agrees with it. The selenoid is not tripping I left the stand open last night so I could watch and hear if it shut off. The only decoration I have in the tank is a small piece of granite that I have my anubia anchored to and an older but pretty solid piece of driftwood. The substrate is pure flourite and there aren't any fertilizer sticks or the like in the tank.

Anyone could my water be naturally buffering the PH ? If so what are my options ?

Scott

 

Re: Reactors, KH, PH, bufferring, was (Major help needed)

Replying to my own question after doing some web reading and talking to a chemist friend the answer to my question is yes my water is very likely buffering the PH. Likely I have reached an equilibrium point that eventually I should go through. If I understand correctly though I am probably slowly lowering the KH of my tank but I need to do some more research. It looks like I may need to start adjusting the the water a bit before adding it to the tank or switch to doing partial changes with RO water. The article here http://www.cichlid-forum.com/articles/gh_kh_ph.php does a decent job explaining it.

Scott