Got the Marine Pure spheres installed under the skimmer. I was able to fit 10 of them in there with plenty of space...maybe could have gone for 2-3 more, but I wanted to be sure none of them touched the skimmer and caused any extra noise. Plus, with 10 of them I've added 2400 sq/ft of new surface area for bacteria, so I think that's probably plenty. Even after rinsing them in RO/DI water they still made my water a bit cloudy, but that's slowly getting better. I took the opportunity to take apart my skimmer and clean it since I had to remove it to put the spheres in, and it's SO quiet now that it's put back together and running squeaky clean. Guess I'll have to make a habit of cleaning it more frequently.
I also picked up some Coralife fine filter pad and cut it down to size to fit on the side of my egg crate media basket in the middle chamber to add a bit of mechanical filtration to catch all the fine particles now that the foam block that came stock with the Evo is gone.