Yes I have to do that also with the edges of my 30g. I clean it every other day when I clean the glass so it's not that bad. And as for the screen top, if u make it black u can make it so it fits inside the tank instead of on top. Just need to ge some small pieces of acrylic and glue them on the frame. The acrylic will hold on to the glass on ur tank and make the top look like its floating. Also by having it that way the mesh will cover the overflow. That will help keep out the fish from jumping in the overflow.