Aquarium Plumbing Question, wall accessories?

Currently I have an overflow box settings as part of my project, but need I need to know what size suitable for closure. The holes in the overflow box is 32mm large size so I need closure? I searched for a bulkhead 32 mm, but the '32mm 'seemed to be for the tubes, but the hole is in fact conform to the description said that "requires atleast a hole 42 mm. If anyone knows what size I need help closing, if you get me a link to a shopping site in the UK to get the 10 points best answer …. first come first served! Thanks in advance: D

Finding the right size bulk heads is a pain. I know this is not the best answer is not even what I had to do was take a piece of paper, put it against the hole, the shade with a pencil so you have the exact size of the hole and go to a shop specializing in saltwater and the most appropriate match heads. A little secret, most people just get PVC fittings with a tube of neoprene on the inside of the tank and tighten them. I personally bulkheads I have most of my tanks while I'm drilling a lot more of them soon and I'll just go w / Accessories PVC-strengthened the glass with some of neoprene or other type washer inside.

60 Gallon Reef Plumbing Test

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