I'm looking in to upgrading to a UVB bulb like Powersun or Westron but I'm not sure what kind to get because some are internal ballast and some are external. I tried a Powersun last year and I got real ticked off when it got knocked to the floor and broke after a freakin week. What are the pros and cons of an external ballast? What does that mean exactly?

Thanks for any advice.
Jessica
www.scalywonders.com