Upgrading questions

[the reefer]

Hey everybody. Right now I have a 12g nano mixed reef with LEDs right now but am interested in upgrading to a 25g marinland cube. Not a big jump due to space but double from what I have now is better.

Now my question is what return pump, skimmer, etc would b best for a 25g cube with mayb a 10g sump. If I can fit it if not then a 5g sump?

Thanks