mh light bulb question

[rayyue]

i am using a coralife 150w (14000k) mh clamp on fixture and need to change the bulb pretty soon.
and want to buy the new bulb in boxing day sale.
but planning to change to 20000k bulb.
want to know can i change to the other brand like ushio or megachrome 20000k? or only can use coralife bulb for coralife fixture?
if i can use the other brand, ushio and megachrome which one is better?
thanks