I'm hoping to breed my bristlenoses someday and have prepared a fry tank for whenever they decide to make me a grandpa.

Would I be better off putting the filter on the main tank and using a sponge filter until the fry are a little bigger? I'd rather not buy a new, ugly sponge filter, but will if it is necessary. If I do go the sponge route, what's the best way to set it up?
I know there are plenty of experts here. Could a few of you suggest a good setup for me? I have time before any babies arrive so would like to get all the kinks out early. Thanks in advance!!!
Andy