40 psi!
I'd be a afraid of popping my reactor (has happened to me once before already, so I know it can happen!) Make sure your output can't clog.
I dunno ... maybe there's a reason these regulators are the most cost-effective? Everyone I know who has one has the same complaint, that they require extensive fiddle-faddling before you hit a steady state.
I'm curious, what kind of bubble rates are people using with these Milkwaulkee regulators (with built-in bubble counter).
I can't run my reactor at 6.7 pH unless I have a bubble count near 100 bpm. Some people have told me that 30bpm should be plenty. For me to run 6.7 at 30bpm I'd have to have an effluent rate near 15 ml/min.. Which I've tried, and it simply does not maintain the levels in the tank. Where things stabilize is at 60 ml/min and the super fast CO2 bubble rate.