[MasterBaiter]

Oh now I understand the reason for the flange. I thought you wanted to run a hose to a pump or something. The only problem I see with a flange is that it would raise the edge of the hole pretty much defeating the reason for the hole. If you are going to drill and are concerned with absorption maybe paint the exposed glass.

I figure this winter I would build a wooden slat type bottom for the compartment. Enough to keep anything out of the water and ventilated so it might dry.