The bottom refractory in my EKO is shot. Next time I move it to clean the bottom out, all I will have left is chunks. I've got some Ideas that I like better than the basic U blocks that came with it. I've seen the mix used to make refractory, but I'm wondering if anyone has done it for one of these boilers? Will it hold up over time? Does it need to be fired in a kiln before using? Any other suggestions? Thanks for the help!