Help with sump design

[Nano]

ya float goes in the return, I put the hose from my ATO in the inlet though so it mixes it bit before getting to the display.

that should be a good size return, I know the skimz sk181 skimmer is about 8"x8" and rated at I think 180g? (dont quote me on that) but the way you stock you'll want a heavy duty skimmer