I am getting 6 baby chicks next Thursday, Mar 13. I'm using a 31 gallon plastic tub for the brooder box. For heat, I'm using the Brinsea EcoGlow 20. Is it OK to put the heater on top of the pine shavings, or should I use rubber shelf liner on the bottom like I've seen on some chicken blogs? Will the chicks try to eat the pine shavings. Also, how much of the shavings should I put in the box? Can you tell I'm a nervous chick mom?