Bought this tank and it's not drilled at the top of the tank. I was wondering what I needed to do in order to make sure that it won't overflow my sump if the power goes out. Please let me know what I need to do in order to ensure this.
If you don't already have a sump, you could use a caniser. If you have the sump, plumb it straight up into a tee (to vent it) and then down to the sump. The tee will determine where the water level will be.
simply add a stand pipe, come 90 degrees upward to the hight you would like to go on your aquarium just make sure its all water tight to the bulkhead so that you don't have a slow leak into the sump if the power goes out.