I'm about to buy a 100 gallon aquarium (used) but it doesn't have a lid. It was used to house turtles so I need to know what size glass lid I need to buy? I've been trying to get the seller to give me the exact measurements but all she can give me is the measurements of the two squares on the top. It's like a plastic frame that sits on the tank. The measurements for each square is 16 1/2 x 22 1/4 which equals 16 1/2 x 44 1/2. My problem is I can't find any lids that match that dimension. Am I not measuring this right? Does anyone know where I can find a lid?