I really just went through this same series of questions! And just a few days ago my husband made a totally shady parking lot deal for a 20 pound bottle of CO2
I've read that some people drop their pH to increase CO2
uptake, but fiddling with pH is risky.
I guess the question would be how you are planning to change either pH or kH
I did not do the citric acid method. I used yeast, which actually did a good job adding CO2
but also (TWICE in less than a week) the yeast itself. With yeast, you add a bit more sugar and get a bit more bubbles. Lots of bubbles is the goal.
Whatever you do to make the bubbles, make more of them.