How much ohms it will read if it is good, or what can of reading I should get if not good

I recently remodeled my basement into an office and I installed nine new fluorescent fixtures in the ceiling. They are your basic two bulb (@ 48 inches long) hanging shop lights. I purchased all new bulbs ( GE kitchen & bath F40T12). The package states that they should last 9 years (six hours per...

After purchasing and then installing three (3) of those new fluorescent bulbs to replace some of my incandescent bulbs, I have some questions. 1. I hear a low volume “humming” in 2 of the 3 bulbs. One is louder than the other, but there is one as quiet as a sleeping baby. Is that noise...

I know that over time the power spectrum of a fluorescent light changes. You start to lose the shorter wavelengths (UV, blue) as the phosphors wear out. I also know that plants need those shorter wavelengths to be happy in an aquarium. So, my question is, how often should I replace the...