Are you sure it's the bulb? How old was it? MH
bulbs last for years, although the color spectrum does shift and it starts losing PAR after about 1 yr. I've been using MH
's for 20 yrs and never had a bulb actually burn out but I do change them every 18 months.
And yes, a 20k bulb will be more blue, but will also have less PAR than a 14k.