lighting obsession sounds like rubbish to me

I'm setting up my first nano-reef. I'm reading some debates on
lighting, especially whether or not to use a glass hood. A common
concern I've heard is that glass will limit the transmittance of
certain wavelengths of light to the detriment of coral growth.

I scuba dive, and I've regularly seen photosynthetic corals in 70 feet
of water. mind you, the water is very very clear in these dive sites,
but does 1/4" of glass really change the light spectrum more than 70
feet of water?

I mean this as a serious query, because I honestly don't know. I lean
towards a glass hood to limit evaporation (although if temperature reg.
is a problem, off it goes) but I'd like to hear why a glass hood is
bad.

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Fjord