If the filter isn't pressurized shouldn't be a problem.

Aeration is as important in the filter as the pond as the bacteria that do
the job are aerobic. Depending on one's filter, just aeration alone within
the filter can improve it's effectiveness. ~ jan

I have just purchased a filter it's a pond genie 48000 with 2x25w uv lights
in the lid,
the place I got it from the dealer told me to place an air line and stone in
the box to help disperse the gasses, my question is
Should I do this as it means drilling a hole into the top of the lid to pass
the air pipe into the box, obviously I will make the hole a tight fit but
also would it cause any other problems.
And has anyone else done this to their filter.
Thanks
Mostyn

~Power to the Porg, Flow On!~