I've had this idea for a while that I just haven't tried yet. I've been considering adding a cheap low range flow meter to the output of my CO2 bottle. I would then adjust the CO2 flow until the PH of the water is where I want it then record the flowmeter reading for future use. Then when I change out the bottle I can just adjust the valve until I get the same flow rate as I had before. I was thinking this might be easier and more consistant than a bubble counter. Not only that on my big tank the bubble rate thru my bubble counter is too fast to count.

I know that Dywer Instruments makes some very cheap little plastic flow meters that only cost a few dollars and are accurate to 10% or better.

Any thoughts on this?