Should it be safe to operate germicidal tubes in fluorescent fixtures that have milk glass diffusers? I have a couple of 4 foot fixtures that have milk glass diffusers that I am considering running G36T8 tubes or G40T10 tubes inside.
Most of the time probably OK. I won't risk though. If you want a nice low pressure mercury color tubular lamp, go to a friendly local neon maker and ask for a mercury filled tube in clear glass. Cute and guaranteed 100% UV safe. You can order even Ne + Hg fill for some awesome effects!
Also, shining strong UVC on plastic diffusers may turn them yellow/brown rather quickly, ruining a look of otherwise nice fixture.