I just took mine off because they cut down on the light for my corals. Have noticed a great improvement in the lighting. I have a 30" deep tank and now the bottom is lit. Think twice before spending that money for glass tops...you may not like them. I have not noticed a diffenrence in the evaporation, I am still topping off at the same rate as before.
If you are bent on getting them....my husband put acrylic on his tank. He put cabinet handles on them and just lifts them to feed or remove.
HTH good luck