Colin @ Coral Ocean is the only one I know of who currently sells replacement bulbs. King Ed's has throw-away 10,000K & Actinics. Colin has 6400K & 20,000K blues that are replaceable. Also, he can now order High Output T5s for about same price ($30+). I have 2 @ 2ft, 2 @3ft & 1 4ft 20,000K & the blue is really strong & beautiful.