New Sump! And need some advise!

[rebelprettyboy]

I bought an Oceanic 1 Model Sump.
I know it could be made better so let me know what I should add. I want it to be a sump/refuge?
Measurements are 24L, 13W, and 17T. Dont know the gallons of the tank I forgot the forumla
heres pics of the sump

 

[rebelprettyboy]

Woops didnt mean to add the new 5.5 gal tank lol

 

[rebelprettyboy]

????????????

 

[rebelprettyboy]

Heres the sump to everyone who helped me w skimmer? which one will fit in here and ...