What I did, step by step:
result = great co2 distribution around the tank
- emptied an old internal filter of all the foam media
- made a hole in the basket for an airline (i just pushed the plastic bars through)
- put a glass / ceramic diffuser in the basket and connected up to my co2 supply
- put bio media (any type will do) on top of the diffuser and filled the basket back up
- attached the basket back to the powerhead
- i did this on a Fluval 1 internal filter i had lying around. Cheap, simple and easy to do
result = great co2 distribution around the tank