Is the 5.0 a ReptiSun? The brand is important as many so-called UV bulbs don't produce much of the correct spectrum. It will depend a lot on how close your cham can get to the bulb and how long it spends under the light. UV radiation typically doesn't penetrate farther than 12". Put the basking spot perch so the cham will get closer than 12" to the UV bulb while it is warming up for the day. Remember to change the UV bulb every 6 months also.