I would recommend maybe switching out your egg crate top, for a smaller holed screen top. One like this....
http://www.bulkreefsupply.com/catalo...d/1810/.....If possible.
The holes are a 1/4 inch and not 1/2 inch. You may not think it would make a difference, buy it might. Couldn't hurt.
You can get the supplies for the frame, at home depot, and the screen possibly from someone on the forum, saving you on the cost.
Its just an idea. Merry Christmas!