If you want to spend some money on a very versatile spray bar, the "Eheim install set 2 spray bar 594" will attach perfectly to Fluval 306. It has a quick disconnect and there are many modification pieces for the spray pattern. I have mine with the additional flow indicator mounted on top.
Just make sure to get the 594 which is .65 inches and connects to the grey end of the Fluval hose. The 494 is .5 inch and will not work.
http://www.amazon.com/gp/aw/d/B00176HKRWOr
http://www.bigalspets.com has the set and many of the attachments for decent prices.
The PVC spray bar VC mentioned works great, use one on another tank.
But my RES tank had protein/oil slick issues and the Eheim spray bar has an aeration attachment that solves this for me and eliminates a few dead spots in the tank flow.
Good luck!