Just had a litter of babies and was worried about the security of the lid on my 10gal, even with clips. Seemed like there was still a lot of play. So I went to wal-mart and got some foam window weather striping for $3 and put it around the inside edge of my tank lid. The clips compress it down like a gasket so there is no gap. I'm hoping this keeps all the wigglers from exploring to far.