First tank was a biocube 14 for me and was extremely successful at growing softies, mushrooms, and LPS. Its still going to need some time to cycle but if you throw some hardy fish in there like two small clowns that should be fine. I used an entire bad of super fine sand in my system and had tons of healthy little critters living in it by the time I took it down.
First thing you need to do is take the bioballs out and remove the false floor from chamber 1 so you can put in a little heater although with the summer coming, unless this is in a cold basement or something you should be fine without one. I added a Hydor Rotating Water Deflector to mine and did not use a powerhead of any kind. Relied on the deflector and the return pump for all the flow I needed. I am a big proponent of using an InTank Media basket in biocubes with atleast filter floss on top and chemi pure underneath.