Nano reef sump.

[Twinn]

Do not use bio balls, if you need to filter use something like filter floss that you can change. Bio balls will hold onto nasty bacteria and cause problems for tank.

[Wayne]

Yeah great idea to add a sump, the more water volume the better! Also these little nanos look awesome when they are nice and tidy

+1 for not using bio balls, I would just add more live rock and use a filter sock personally.