Anti-siphon holes
For a long time, I hated the returns on my tank. InterAmerican drills the return hole in the overflow box, below the teeth. On a larger tank like mine, a couple of inches equals a lot of water in the sump. So I solved it by adding twice as much locline, and had it shaped in an arch. At the apex of the arch, I drilled three holes in the underside to break the siphon and stop draining so much water. This worked great, until about 6 months ago when I soaked the locline in muriatic acid, which cracked the joints and allowed more water to seep out quietly.