Wet/Dry filter setup?


Reefing newb
Hello everyone. I am trying to make a wet / dry filtration system for use with my 55 gallon octopus tank. I recently purchased a 20 gallon tank to use as the container, an Eshopps PF-300 overflow box, an Eshopps PSK75 in-sump skimmer, some bioballs, and an Aqua-Supreme 400 GPH pump. I have a BASIC sketch of how I'm going to set this up, but was wondering if some of you guys could take a look at it and tell me what I can improve on.

Can the bioballs be completely submerged?

Here is my sketch:


Thank you!