Anyone with experience on this?? Thanks for your help. I have a 180g with a corner overflow. Two 1" lines inside the overflow -- high on its back wall --feed my sump. The upper of these two 1" lines is 2/3 full as it pours, so I think that MAYBE more flow rate to the sump is possible - not sure. Two challenges. 1) My tank water level is too high. The water brushes up against the glass cover, though there is no danger of it spilling out. Aesthetically though it sucks. 2) I am trying to switch from my current Little Giant 3MDQX-SC pump (916GPH @ 5ft) to a new Iwaki MD40RLXT (1140GPH @ 5ft) and wonder if the overflow can take it. When I add more water via a Python hose running from my sink (while the Little giant is running), the water level in the overflow starts rising, so I'm really apprehensive about switching to the stronger pump. I can't drill more/bigger lines--not an option. Suggestions? Do I break off some teeth of the overflow? Or cut the notches deeper? Throttle back my new pump with a ball valve? Or forget the stronger pump? Ideas? Thanks...