Tank lid? Good or bad?

[c_scherer123]

I have tried hunting for info, but I am coming up pretty empty handed. Any opinions or links would be appreciated.

Is it better to have glass tank lid on the tank or not? I know our freshwater tanks are hit hard by evaporation and heat loss when we remove the lids.

Some people have eggcrate to allow light and block flying fish. Wouldn't that melt under the lighting? Doesn't eggcrate block some light anyways?