home-made smoker

I built the double barrel smoker and have turned out good meat. I have a general question. I am want to know the best wood to use? I'm having issues with controlling a good slow burning temp. Bottom barrel is fire only, top barrel is sweet smelling!

Don't know if this is of any interest, but I made a pretty nice smoker out of an old water pressure tank: First I cut the fire door opening and removed the bladder: (nasty and smelly) Next is removing a safety dome located about 2/3 of the way up inside the tank: (This is used for the...