Hi,
I have a new beardie, the vivarium is wood, 36" long, 24" wide, 16" tall (inside floor to ceiling).
I have a new 24" T5 fixture for the UVB mounted on the inside of the vivarium, it is about 2" tall, so there is about 14" from the floor to the UVB bulb.
My beardie likes to bask on a log about 8-10" away from the UVB bulb.
Should I use the T5 10.0 bulb without a reflector, or a T5 5.0 with a reflector? I am concerned about too much UVB at close range.
The key is to provide a gradient so you'll want an area with relatively low UVB along with an area for basking with higher UVB to allow for self regulation. Put in some hides and shady areas and that will help quite a bit. Going by Taterbug's lighting guide https://sites.google.com/site/thelizardmadness/lighting-guides, it seems like you may be best off with an Arcadia 6% w/reflector at 10'' or going with the 12% or ReptiSun 10.0 without a reflector to cut some of the exposure. I like to shoot for 3-5 UVI in the basking site with gradients through 1-2 and down to 0 in different areas.