this is an old thread but I have to weigh in on this one. Billybono said an opd tank would not work but I have to disagree with him. You can only get opd tanks filled now and thats all I have. I have no problem refilling the 1 lb. bottles. just freeze the small bottles for 15-30 minutes, attach to the adapter which is on the 20 lb. bottle. turn the 20 lb. bottle upside down and fill for 1-2 minutes. hope this helps.
HIMO