Originally Posted by reinstone
would i need to cover a blacklight with foil
A true black light emits almost entirely in the UVA range, and you wouldn't want to be bathing your beer with that. So, yes, some kind of light-blocking would be a good idea.
That said, if you're going with light bulbs, a low-wattage incandescent would be the better choice. There's no starter or ballast circuitry needed, incandescents put out virtually zero energy in the UV spectrum so there's no need to shield them, and with the wide range of wattages available you can dial in what works best at a modest cost...