temp control on greatful smoker

i can't get my new smoker to keep low temps running a gas element from a turkey fryer and my temps are on the lowest i can keep is around 280 would like to get control down to around 250 and lower to smokr other things thinking of maybe switching to electric if i could get some info like what would be a good element and some guidence on how to go forward thanks

http://www.smokingmeatforums.com/forum/thread/101974/fridge-finished