I personally do not use anything lower than a 10.0 as I feel a wild uv index cannot be created with anything lower in a 4 feet high cage above mesh for a veiled or panther. This is what the person who makes the Arcadia lamps told a chameleon keeper who was using a 5.0 on top of his 4 feet high reptibreze for a veiled recently.
"A lamp cannot be chosen simply by species! we need to re-create the parameters of the wild in a safe and sustained way. we need to incorperate the light and shade method and we need to keep in mind the limitations of the tech that is available to us. A 5% T8 lamp through a mesh and with a basking spot of 12" under the mesh which is too high really will only be re-creating the UK at dusk. compare that with the Index that they obtain in the wild and it is polar oposite in most cases.
as with all these things re-create the wild and you wont go far wrong,"
Uv is one of those subjects that really interests me and I do love to discuss it!