newbie: which way up does the filter go??!

I have a fishtank in a old imac and I have all the bits.. But the one
thing Im not sure about is which way the filter goes up?!!
take a look at "DSC_0016.JPG" at
http://homepage.mac.com/willwade/PhotoAlbum16.html
That should help explain the issue.
The filter has a small hole located at one end (in this picture its at
the rear top). The thing is there is a arrow on the filter suggesting
it goes the other way round.. But the bubbles arent quite as bubbly!!
(the bubbles come through the plastic casing when its the other way up
too)
Any ideas? Am I mad? (yes!)

will

will wrote:

I have a fishtank in a old imac and I have all the bits.. But the one
thing Im not sure about is which way the filter goes up?!!
take a look at "DSC_0016.JPG" at
http://homepage.mac.com/willwade/PhotoAlbum16.html
That should help explain the issue.
The filter has a small hole located at one end (in this picture its at
the rear top). The thing is there is a arrow on the filter suggesting
it goes the other way round.. But the bubbles arent quite as bubbly!!
(the bubbles come through the plastic casing when its the other way up
too)
Any ideas? Am I mad? (yes!)

will

No idea, but that tank looks far too small for any goldfish!
Betta yes, Goldfish no!