Do you plan to eventually replace the coral skeleton with some live rock? I think that would make it look a bit more natural.
Eggcrate normally won't cut that much light; however I would use some mesh instead if you want a cover. You also can't compare the before and after pics for tank brightness and the background lighting is totally different in both pics.
i would get rid of the egg crate. look at the before and after pictures of it and you are losing a massive amount of light. what kind of fish are you going to keep? you might not need a cover. the powerhead looks good. do you need a small piece of live rock to seed it?
Eggcrate normally won't cut that much light; however I would use some mesh instead if you want a cover. You also can't compare the before and after pics for tank brightness and the background lighting is totally different in both pics.