Pro-SE Series CO2 Regulator W21.8×14

The CO2Art Pro-SE Series is a dual-stage CO2 regulator for planted aquariums with a built-in 12 V DC solenoid valve.

According to the manufacturer, it suits both tropical freshwater and marine aquariums. The W21.8×14 thread (BS341 / DIN477) is the European standard used by most refillable CO2 cylinders.

The dual-stage design stops the output pressure from rising as the cylinder pressure drops, so there is no sudden burst of CO2 at the end. It works with any cylinder size. The working pressure is adjustable up to about 40 PSI, roughly 3 bar. The regulator has a needle valve, a bubble counter with a built-in check valve and two gauges, one for the cylinder contents and one for the working pressure. The solenoid's power adapter runs on 100–240 V.

Set the working pressure for whatever the CO2 goes to. The manufacturer suggests 10–20 PSI for reactors, 20–30 PSI for ceramic diffusers and 30–40 PSI for inline and high-pressure diffusers.