I dont think a protein skimmer is necessary if you do weekly 20% water changes. The Fluval skimmer for this tank sucks in my opinion. It was loud and a pain in the butt and not worth the hassle.
I am using the inTank media basket in chamber 1 - filter floss on top, chemipure blue nano x2 in the middle, fluval ceramic rings and marinepure balls at the bottom. I also have the middle chamber filled with marinepure balls. I'm very happy with this. Water is crystal clear, fish and corals happy, lots of purple coralline algae, and only a small amount of ugly algae on the glass.
I upgraded the pump to the Sicce 0.5 for more flow and use a random flow generator return nozzle instead of the two stock nozzles.
There is lots of info in the thread below:
https://www.reef2reef.com/threads/show-your-fluval-evo-13-5.292874/page-16
or search all the Fluval Evo threads:
https://www.reef2reef.com/search/3960988/?q=fluval+evo&o=relevance&c[title_only]=1&c[node]=89
