Notching glass for external overflow

[Myka]

Egg crate restricts flow a lot less than teeth do. Personally, I would do a horizontal 3/8" slit instead of teeth or egg crate. Easier to do, looks better, and doesn't restrict flow like teeth, or to a lesser degree, egg crate does. You can use the same linear length as you would with egg crate. The only thing you have to consider is to not buy snails that are smaller than 3/8". You should be making this same consideration if you used egg crate on the overflow.