Tetra-tec makes a cool filter, I had on running on a 7g mini-bow for a while. I believe it is the PF-150, it provided good flow for the tank and the it has a built in heater and wave maker. I would recommend doing a 20% water change every week also. Let us know if you have any more questions concerning nano reefs. Theyre cool tanks to have, Ive had from a 2.5g to a 15g nano so I can help you out if you have any more questions.
Sean