Do eggs need air circulation underneath them or might my eggs on perforated shelf liner on tile work? Second timer hatching. Using ceramic tile (heat sink) under shelf liner (soft and spongey.) I use 2 quarts of water (heat sink) and one bulb running all the time and one on a digital thermostat. Computer fan and styro chest. Here is my setup. I plan on putting up a chick guard before the hatch.