Originally Posted by BSDeality
how many GPH is your pump? that will determine how big to make the lip. I would defintely start small, you can always widen it if its pushing too much over and spilling. Figure 1200-1500gph for every 1' of lip 1" tall.
Problem with that might be kinda hard to make the cut once it's in place and full of water. I think he needs to guesstimate it right the first time. I guess it woudn't be that hard draining it and pulling it out to recut but if you're like me you don't wanna do too many do-overs!
Good luck, keep the pics coming! Looks great so far.