Its a slot cut in the lid not a hole, and i did it with a hacksaw. Didnt fancy trying to thread tubing and cabling through a hole.
Had that for 2 years and nothing has jumped or crawled out. There is maybe 3 to 5mm tolerence around the tubing to the slot i cut. Not a very neat job if inspected closely, but serves a purpose and the project box tidies everything up and hides my poor workmanship.
Would doing something like this work? I cut the lid so the tubing could go into the tank, then got an electrical project box, cut the back out of that also, and glued it over the hole in the lid.Attachment 319486