Just to throw this in the ring, I am pretty sure I have the same sundial fixture you have (T-5, with actinic, full spectum, and LED
's) If it is the same the bulbs are 2 of each kind. I would purchase some back-up bulbs to have on hand. I had a problem where one light went out, but that kills the entire circuit and neither of the type of faulty light will work. You have to figure out which one went dead and change it, then the other one will still work. I have 2 spares of each on hand, just thought I would offer that advice up.