The Reef One biOrb/biUbe One Way Valve provides Extra insurance against the unlikely event of water leaking into your air line, or for extending your air line. At least every 6 months a check should be made by disconnecting the air pump and lowering the air line below the water line. In the unlikely event of leakage a one way valve can be fitted to the air line. This should be fitted six inches from the air pump. If you wish to extend the length of the air line from your aquarium it is advisable to do so with a one way valve.