This precision flow needle valve from Red Sea is designed for aquarium use; independent so it can be installed in-line with standard CO2 tubing, it mounts on the side of your tank rather than on your canister so that you can access it easily for adjustment or shutoff. Produces stable C02 flow as low as four bubbles/minute.
Make sure that the valve is fully closed by screwing the parts together in a clockwise direction.
Connect the CO2 tubing from the regulator or solenoid control valve to the inlet of the valve and secure in place with the lock nut.
Start the flow of CO2 from the regulator.
Slowly open the valve by rotating anticlockwise until you can feel or hear the gas flow stops and in this position attach the valve to the sidewall of the aquarium with the suction cups provided.
Connect the outlet of the valve to your bubble counter/reactor.
Adjust the flow to the desired rate by rotating the lower half of the valve assembly.