Help with small refugium setup?

[wonderd4]

Hello everyone, I have a 3.7 gallon tank I recently bought and I'd like some help setting up the rear of the tank. The tank came with the filter, bio balls and sponge as seen below. What should I put in each section of the back? Do I ditch the filter, sponge and bio balls? I will be using the tank as a FOWLR only right now. However in the future after I upgrade my lighting I may try some corals.

 

[santamonica]

Generally best to let the sand and rock do your filtering, and let the food particles circulate around. So you would not need the floss or foam. And once your sand / rock is cycled, you won't need the bio balls either.

Letting food particles circulate will give you stronger/thicker periphyton on the rocks.