Broken powerhead

[fraley]

Hi ive recently bought a second hand tank with undergravel filter and two powerheads, one of which is an aquaclear 301, i understand this has an airline attachment but not sure what use this has.
Also the other, which has no name or markings, doesnt seem to work at all, does anyone know if there is a regular problem powerheads have other than getting clogged up i suppose??
Any help would be great,

[Lady Hobbs]

I had power heads when I had under gravel filters. Got rid of the filters and now have no need for powerheads. You can use them if you wish to add aeration to your tank, however, or wish to use a sponge filter.

[fraley]

Any idea about using it with an airline?