Any reason not to use a blacklight?

[The Serpent Merchant]

The black light will not hurt your snake at all, i have a 6 year old uv light on one of my bps cage. The uv light will not give off enough heat to increase the temp with in the cage. Try RHP like everyone else suggested, you could use a small one and it will increase the temp just enough to heat up the cage for a proper gradient.

If the bulb is actually inside the cage it will increase the air temperature a few degrees. In my cages I see a 3 degree difference between when the 18" fluorescent tubes are on and off.