I have reasearched it, and if you could provide with a link to help, that would be great. But I'd like to ask the people who have created/made an OF, preferably a C to C overflow- glass- for a back drilled tank. HOw do I get nice, uniform slots in the top. I know there are alot of over options, including having none and fishing things out of the overflow often- already talked to someone who does just that. If I used acrylic (easier to notch), I've read that acrylic wont stick to glass that well? ? If I'm doing a C to C overflow on my soon to be wet 180- it'll be a 6ft. piece of glass to notch! I could put pieces of eggcrate is, parallel to the front on the OF, and held in place with small PVC pieces, or I could use the plastic/vinyl gutter guard- which has a Ushaped grove down the length that snap over the upper outer edge of the gutter; this would snap down nicely over the top of the glass- like it does the upper outer edge of a gutter. Trim it to fit, etc. (I'm currently using one to wrap around my 'DIY intank overflow' How have you done it? Any other ideas?