500 gallon smoker first build

[jeffthewelder]

I’m building a reverse flow smoker out of a 500 gallon tank so far I have the doors flume and firebox done but kinda stuck on how big the chimney needs to be the fire box is h26 x w39 x l38 and my opening is 1/3rd of the bottom of the tank what do y’all recommend this is my first smoker build building for my uncle who does benefit cooks to help kids with illnesses and people who are going through hard times