Aqua Medic Membranereactor, available from Swell UK at discounted prices.
The Membrane reactor contains a gas permeable membrane tube, impermeable to water. When connected to a CO2 unit, the gas diffuses through the membrane into the water - bubble free, with no losses.
The Membrane reactor must be installed in the aquarium in an area of rapid water circulation. The deeper the reactor is fitted in the aquarium, the greater its capacity.
It is manufactured in 2 sizes: