I just read the instructions (dumb idea, I know) for some fluorescent
fixtures I bought sometime back, for my shop. Anyway, it says the
fixture is only for 2700K, 3500K, and 4100K tubes. Why does the
fixture/ballast care what phosphor is in the tubes? I was planning on
using 6500K tubes (like I have in similar fixtures). If there is good
reason to respect these instructions, I'll probably change them over
to LEDs but it's a lot of tubes to trash. The coldest white LED tubes
I've seen are 5000K. I'd prefer 6500K but 5000K would probably work.