Ironically, I do have a shield for the heater, but was reluctant to use it because the one in the tropical fish tank got melted to buggery when I forgot to turn off the heater during a water change, and I panicked over the damage it would do to the fish. I am a dopey thing and didn't want to make the same mistake again. So I made a different mistake! Sticking with no heater now definitely :-) thank you so much for all your help, I really do appreciate it x