How can I get my gerbils to stop biting the bars of their high rise tank topper?

Question

How can I get my gerbils to stop biting the bars of their high rise tank topper?

Answer 1

put other things in their tank to take up their biting habbits like wooden treats you can buy. Also take away things that they climb on or sit on to reach the top of the tank at night because this is probably when they are most active?  

Answer 2

I'm fairly sure you can't.

gerbils teeth continually grow and it's just something they do

my gerbil drove me mad when he kept doing this at night