MyFishFinder.com Just like iceshanty but warmer
I also have been doing this for years. I can refill 17 per a 20# tank. You will get the ocasional leaker. I mark them with a sharpy marker and dispose of them when empty. Freeze the small tanks before filling and use commen sense.
wal mart will trade you an old 20# tank(ive brought a couple in i found in the woods hunting) and trade you for a brand new filled rhino tank for 17.99. then you dont have to worry about getting old tanks filled. the new opd valves sure are a good idea because there sure are a lot of idiots at propane filling stations . i think im paying 7 bucks for a fill down the street billybono