Sorry, I must have missed this one. I have not been around in a while. These pics should help you. I am going to also say in a 30 cube, the 500 would be too much. I would go with a 9010 for sole filtration, with 2 powerheads.
Here is a few pics of an my old 37 with a 500 installed. It was a good fit imho, but in a 30, it may be too much.
http://reefcentral.com/forums/showthread.php?s=&threadid=887949
I have since move everything into a 75, and everything is thriving. all corals in the picture have increased in size 4-5 times in one year. The small hammer is now a 30-40 head beast, as well as the frogspawn, and pretty much all of the corals in the tank. I pretty much have the simplistic approach that Tunze affords to thank for it. Thanks Tunze !!!
My current 75 BB "Berlin style" set-up is a Reefpack 500 running a 9010, Tunze Kalk reactor with osmolator. 3 powerheads on a wave timer. The filtration side of the 500 is only used for flow and a place to hide the osmolator sensors........no filter media at all. I love it. All corals and fish are thriving together, sps,lps,gsp,shrooms,etc. with no undesirable algea. Lighting is bouncing between halides and vho's (cant decide which I prefer).
Anyway.........hope the old pics help. You cant go wrong with Tunze.
Later...........Herbie