Hello, I bought a 3 tub 41qt rack I forget what brand cause it was a couple years ago I bought it with the hopes of getting back into ball pythons. I finally bought a nice adult normal female and have been keeping her in a tank for the past month or so bit have been having trouble keeping her humidity up so I decided to move her to the rack. My question is in front of the tubs there is a little hole to put something in to prevent the tub from being able to be pushed out, what do yous suggest I use to stop that from happening. It's a pretty tiny hole too dark to get a picture of.