Enlarging bulkhead hole

[Doug]

I think best to error on safe side. I will drill another 1 in. as planned on rear, giving me the 4 holes. Im going to drill it a bit more to the open side of the tank and not closer to the side glass. I will just enlarge my overflow to 1ft. Takes away more tank but I will have a duzer of an over flow and herbie/beanie thing or whatever its called.