Okay. Do you have a drop checker? (If not I would suggest getting one. They are cheap, and can give you a relative idea if you have good CO2 in your water). Check for leaks. You mentioned you are at 1 bubble per second. When you find the time increase this temporarily to ~3bubbles and take a pH reading 1 hour afterwards. You should without question see a drop in pH.
IF you do not, then there is a CO2 leak somewhere in your system, or the CO2 isn't dissolving properly in the water (could be an issue with the inline reactor, or as mentioned earlier your lily pipe needs to be fully submerged in water to not lose CO2).
The reason I mention to temporarily do this is you do not want to gas your fish. You'll know this is the case if you see them floating at the top gasping for air. In the mornings after you had the CO2 running at night were the fish at the top of the tank?