Just a heads up... the longer you keep that 50/50 actinic bulb in there with that amount of light intensity, you will most likely see algae develop pretty fast. That really blue actinic light spectrum is really only usable by algae...
The pump is discontinued, it was like 3 years ago when I upgraded it to that model. I'm sure you can still find them new on ebay... but if you need a replacement, you'd have to do a little research. I'm pretty sure they're standard, Outlet Size: 1/2" I.D. Vinyl Tubing, and you just need one that fits the tubing that leads down to the stock pump in the back compartment (like a built in sump). Let's see... the 14g BioCube stock pump (just from a quick google, you should double check this) is suppose to have about 137GPH... non-adjustable. My 404 is rated to be adjustable from 18 –108GPH. There's a 606 model that is adjustable from 82 – 153GPH, which should work.
Amazon.com: Marineland Mini-Jet 606 Powerhead BULK VERSION [Misc.]: Pet Supplies
I'm not sure how similar or dis-similar a JBJ Nano Cube 12g is from a BioCube 14g, but when I changed the pump, it made the world of difference with the new pump running cooler, quieter, and having the ability to reduce the flow. My fish, with the stock pump, (I was a newb and I'm embarrassed to say) were constantly fighting a river of a current...LOL
Here's a video I made 3 years ago when I used silk fake plants thinking it was cool. Notice the blue actinic light... well 48 watts of that over a 12g led to a lot of algae scrubbing weekly!
German Blue Rams - Nano Cube 12g Aquarium - YouTube
Check out my transformation journal from when I started the Nano Cube, to when I swapped out the bulbs, pump, and got real plants and DIY co2. Notice in the pics below the fake plants, when I first got into plants, I got low light ones and still had the 50/50 actinic light w/ no co2... I had an algae farm to say the least.
http://www.aquariumadvice.com/forums/f19/my-12g-nano-cube-fw-its-all-grown-up-now-227698.html
And here's something to consider down the road, if you ever want to switch to LED instead of those PC bulbs and loud fan... check out my retro-fit LED install in my nano cube I just did.
http://www.aquariumadvice.com/forum...elumen-pro-leds-retro-fit-upgrade-267216.html
For now... I'd focus on the bulbs and the pump... get more fast growing stem plants (i.e. rotala, ludwigia, etc.). DIY co2 or pressurized. Dose a good liquid fertilizer like Flourish and Excel.