Well, I'm at a standstill with my calculations. On Feldon's Calculator for propane tanks it wants to know a gallon size. My tank is 30 X 87 and on this site ( http://www.smokerplans.net/index.php?main_page=index&cPath=1_3&sort=20a&alpha_filter_id=50 ) it tells me I have a 200 gallon. The 250 is 30 X 100. I find it hard to believe that 13" X 30"Dia. would be the difference in a 200 and a 250. Any suggestions on how I should proceed with my calculations? Is there a way to find out if Feldon's used a 30 X 87 for his 200 gallon propane tank calculations? Any other way for me to find out exactly what I have?