If you do dig out your pond around the pipe dont let to much pipe show without dirt holding it still or it may bust. Just a thought, I work at a golf course and it happens. It may not matter on a lawn system though.
I have had gar in the past and the shortnose/spottednose are the smallest at around 25 inches, spotted max out at like 45 and longnose and gator gar get massive. Have fun.