Open or closed tops

[Doug]

Your correct Tony. Whatever floats your boat. :D

If I had a hood, I would likely not run covers. But it depends on ones thought on UV & the corals.
http://www.aquarium-design/reef/uvlighting.html

I also use a lense in my pendants or a piece of glass, to filter some of the uv from my arms when working in the tank. My fair Irish skin needs protection. :D