Adrian, it's pretty big when it's completely open, as in large dinner plate sized! I got it about 3-4" across, one of the former members of NTRC used to hang them out, she had tons, all at least 3" across. This one got big quick, and I have a 2.5" one down in the rock work from where it tore off during a transfer to the 90 about a year ago.
Thanks Mike, it's easy to get discouraged at times, I see so many awesome tanks, and while I have good luck with mine, I'm still not 100% happy with my bulb setup. It just doesn't seem to have the WOW factor that many tanks have, but I'm glad that some people like it.
Thanks!