take a look at my thread (cris' 60) and the sump that I've set up. It's pretty easy to put one together on your own. Those wet/dry filters are typical of Fish only tanks. take a look at Melev's sumps for ideas. you don't have to use acrylic. I used a 20L and aquarium silicon with acrylic for the dividers.
The main filtration in a reef tank consists of the sand and rocks themselves. A good protein skimmer and maybe a bit of carbon (personal choice, I like it) are all that is needed.
I would remove the bio balls now, but not all at once. If you removed them all at once then your bacteria population would be severely depleted.
Remove 25% of them at a time once a week. You do need to get these out to help keep nitrates down. In a reef tank you want to either have the excess material eaten (clean up crew) or totally removed (like with a protein skimmer).
Your lighting is T12? Does each bulb have an individual reflector? I am not sure about T12. I personally use T5 lighting (six bulbs) all with individual reflectors and I still have to keep higher light demanding critters half way up the tank.
Basically I don't think your lighting is sufficient for all corals in all locations of your tank, try moving your mushroom up higher (at about half way or even higher).
I like your tank. Just some thoughts on the comments in the thread.