I don't know why you'd want a 50/50 bulb (of any type, T5, MH, LED, PC) over a fuge. The only type of light a fuge needs is daylight. No blue lighting necessary.
You made a statement about the 50/50 not working for you. I replied with an explanation as to why it might not be working. The blue spectrum over a refugium is wasted light. I wasn't suggesting you change your light.