Hey Everyone! I've been reading a lot about multiple filtration and we actually have an extra filter that we "retired" when our LFS told us to get a biowheel filter to help when our cycle stalled. I have a 20g Long stocked w/ 3 platies, 3 cories, and 3 zebra danios. weekly water changes of 30-40% and my pH is steady at 6.5.

This may seem like a silly question but I don't want to mess up what's going well in my tank. Are there specific logistics to adding this new filter? New filter media, plug it in and go? Should I add some beneficial bacteria or will my bacteria from the other filter populate the new one?

Thanks everyone!