Hi guys new to the forum been thinking about building a smoker fo a while and found this site looks to be very helpful. I got my hands on a 325 gallon propane tank and cut it down to 90 in. its 30in. in diameter i put that info into the pit calculator and came up with a 28x28x28 fire box going to cut a half moon into the fire box to match the tank. The question is the pit calculator said a 21in. diameter half moon 175sq in. when i drew that out on 30in.circle on card board 21 in wide its only about 4 1/2 in.tall that only came up to 70 couple sq in. To get 175 sq in my half moon had to be about 27 1/2 in. wide and 9 in. tall . Did i miss read the calculator or did i not figure my sq inches properly. What i would like to know is how tall and how wide my half moon needs to be in my fire box in inches and how many inches above my fire box opening does the top of my RF plate need to be that would save a lot of headaches on my end not to good with the whole math thing. Thanks in advance!