Water doesn't contain bacteria. Bacteria is quite firmly attached to the surface of your tank (ie. substrate, glass, decor, etc.) and resigns mostly in your filter(s).
Stick the new filter on your tank, let it run for a month or two. Sounds like you currently have a sponge filter in your tank? Do you have to pump air into this filter to get it to work? If it is a sponge filter, stuff the sponge into your filter (aquaclears work perfectly in this respect) and leave it at that... you can even cut the sponge up into smaller pieces if needed to fit the filter. I've stuffed established sponge filters into my Aquaclears and run them like that before with no biological filtration problems.
As a side note... UGFs are good filters as well... if and only if you maintaint them well. Although I personally don't use them since I figure there are better forms of filtration out there, I have nothing against them.
HTH
-Richer