Adding CO2 to the aquarium can be complicated, but with the right accessories it becomes relatively easy. Also when you need to attach multiple aquariums to one system, you can find everything you need here.
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CO2 bottles can only be used in an upright position. Some CO2 bottles have a round bottom, making this not possible. This HS aqua bottle base for a CO2 bottle makes it possible to place a CO2 bottle upright in a safe manner. The base is adjustable in 2 positions and suitable for bottles of 65 mm or 80 mm.