To offer my opinion, I wouldn't think of adding any type of cover to my tank. My canopy will keep jumpers under water (as long as it's closed) and their is no way I'm sacrificing even 2% of my expensive lighting to being filtered by the glass. Temp is easier to manage and if you're adding kalk, you'll want significant evaporation to allow the addition of enough make up water to get the kalk in your system.
In the years I've had my tank, nothing has ever fallen in. Overall, I can't think of a good reason to have glass over a tank.

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My cat would love for me to take my glass off, he had some kind of hatred for my strwberry pseudochromis. My bird also loves to sit on the ledge of my tank and given the oportunity would make a nice lunch out of anything in there. Not to mention taking a crap in my tank. I have no choice in the wild kingdom but to protect my sea.

Canopies do wonders for that!

I use glass for the simple reason that I'm very worried about water and salt getting on my lights, and salt creeping down into the working end of the lamps.