No plastic filters out UVB to an extent. It's best to have nothing between the bulb and the enclosure. The 5.0 will be ok for now bt you will want something stronger. Have you looked at lightyourreptiles.com for some pricing? He Arcadia 12% high output (its the desert bulb) is highly recommended for adult enclosures. It will basically have UVB emitter down several feet so your lizard has greater exposure no matter where they climb in the cage, whereas the zoomed or exoterras bulbs only emit UVB down to like one foot so he would have to be directly under it for exposure.