Very cool setup!
I believe a power head would be used to run a protein skimmer for a saltwater setup. Protein skimmers are not effective for fresh water. So no need for a power head!
I would consider putting a bubble wand under the bio balls just to supply fresh air.
For the chambers I would put a course sponge in the top chamber, a medium sponge in the middle chamber and filter floss in the bottom chamber.
Bio Balls are more effective than scrubbies. I would not use scrubbies.