I’m in the process of building a waterfall (well, actually a lazy creak that will empty into a pond, hopefully) in a 72 gal bow front.
I purchased from eBay a glass hole saw and a bulk head fitting from two different vendors. I decided to cut a hole in the tank mainly because I don’t think a canister filter has enough head pressure to pull a 6 inch level of H2O all the way up to the top of the bow front, then down to my floor and then push it back into the tank. I thought it would be easier to accomplish water movement if the water was actually draining into the filter.
I knew the bottom of the bow front was tempered glass, so I drilled a hole successfully in the back corner. I haven’t had the pleasure of trying to fit the bulkhead fitting to the canister hose yet, but I think a 1 ½ inch hole saw with a ¾ inch bulkhead fitting ( don’t forget a strainer) will work best.
I just finished siliconing stantions (last two words spell check didn't like) to my false bottom egg crate and screening the top of the egg crate. My wife just got finished charging four background bark panels from the local pet store for $72. All of a sudden she’s in big hurry because she heard about the frog fest in Staten Island in May. I just say, OK dear.