I believe Eheims use 5/8" ID hose as does XP3.
Here's a thread on the spray I made for both my 55's:
http://www.aquariacentral.com/forums/showthread.php?t=109900
It's been in there for over a month now-still working great. Got flow all across the back of the tank, not just a foot long length as with the original spray bar.
Edit-just reread the thread, made a change to the original design. Plugged up the holes on the rear of the bar with silicon and re drilled with a #42 drill on the front pointing slightly up. Got great surface agitation!