I actually purchased 2 bags of eco earth equivelant to 3 bricks of eco earth, but do i need to replace the eco-earth often? I'll use a sheet of Plexi Glass with a hole in the top for the 80ish watt heat lamp.
I replace my substrate twice a year. I spot clean any waste when I see it but for the most part Pyxies crap in their water dish making clean up pretty simple.
