If you don't want to use the magnets then you don't need to. I used two plastic clamps, one on each top corner to secure it that way because I didn't feel like messing with the magnets. Between those two clamps and a piece of rock laying against it in the tank, the background never moved at all. The rock really wasn't even needed to hold it. If you wanted to, you could run some aquarium silicone on the back and secure it that way.