if ist an Exo Terra canopy they're only designed for use with low-wattage light/UV bulbs that emit very little heat. i'm confused as to why he sold you a blue bulb though, its red that snakes don't notice! if the light is for display/seeing your snake its probably best to use an energy saving bulb and switch it off overnight so you don't interfere with the snake's photoperiod (night/day cycle)
cornsnakes, ratsnakes, bullsnakes, boas and day geckos
Think I will gave to get a different bulb , one that at least lights up the tank Clityle in the evening . The current blue bulb is 15 w and the unit says it takes bulbs ip to 25 w .