I am still new to heat treating , but i am real good at blowing up rock
but the way i understand is by removing the pan you get rid of wasted space and get the heating elements that are in the sides get closer to your sand/rock are increase your temp also the sides and bottom will yield higher temps than the middle makes sense huh , so place your rock acordingly , i also layer tin foil on top of my sand bath to try to insulate it and get higher temps hpoe that helps ... oh and i m still trying to get that rock out to you , i know im a slaker