|The easiest way to remove the trapped air from a canister filter is to raise the spray bar out of the water. Doing this will allow the trapped air to escape. This should be done anytime maintenance is performed on the filter.
Other in-line canister filters such as the Ocean Clear or the Lifegard systems, contain a small valve on the top of the canister. This valve should be opened when first operating the filter to allow the air to bleed from the filter.