Quote Originally Posted by Simplex View Post
I could never understand the space most people place between there rodent tubs. Figured it was for water bottles but i put mine right on top of eachother to save space. I hope i didnt make a grave error.
The gap between tubs is for air to circulate through. It doesn't look like you have much room between each level.

The way it's set up you could just as easily have put the rats in a box with a few air holes.