Ok. So here is the overflow with the back acrylic cover removed. Left to right. Emergancy pipe, trickle pipe (has a small hole drilled on top to create siphon if water gets too high), and siphon pipe. image.jpg
The return section of the sump doesn't hold a lot of water, there is a divider between the main part of the sump and the return, so even if you blocked the siphon and trickle tubes water wouldn't flow over the top of the tank or even to the emergancy pipe because only the return section of the sump gets the water pumped out and the pump runs dry. Most of the water in the sump would remain because it has to flow over that 9" tall divider. So really it's not possible for the emergancy drain to be used in my case, many people need it though. image.jpg
I recently installed a bulkhead in the sump and a 3/4" line straight to the floor drain as well - something not normally done - so I can just add water and the extra goes right down the drain.