Instead of having an actual lid on your tank, I thought of an Idea that you can get a piece of screen. (Dont know the name but it is the screen for patios over pools) Yes you may have to deal with evaporation, but, the good deal with that is that it is like a mini water change. I have a 75g with the screen on with the light over it. The water that gets evaporated is like 5 gallons a week. I can forget about it though. Because I have an eheim filter with the spray bar. I have it marked at 70g full, and when i hear the spray bar I add a few gallons to the tank. Also, I understand that lilly pads cant survive under a standard lid. Now they can! Fish can't jump out, lilly pads can survive, and the evaporation is a min water change.

Let me know what you think about this
Let me know what you think about this
among other things, nitrates don't evaporate. Waht your doing to the fish is detrimental to their health.