I agree with you Allwissend, regardless of method of injection, go slow.
I set mine for what is required to hit my target and a bit more. If your bubble rate isn’t high enough, you won’t reach your target. Trick is to creep up on it slowly until you reach your desired level. System I built checks the pH every 5 minutes and switches on/off +/- .02 of my set target of 6.45. When first set up, the pH would not go all the way down so, open the needle valve a touch more and repeat until the system kicks in and starts taking control.
Here’s a typical day of CO2 injection.