someone will blast me for this, but we use weed burners all the time
for various projects. The ones with regulators are wimpy. the good ones
have no regulator, and will freeze up a 5 gallon bottle in about 5
minutes.

when teh bottle starts to slow down, torch the bottom of the bottle
until she perks back up. you want to warm it up until some of hte ice
melts off, but don't warm it up anywhere near to where the water comes
off the outside of the bottle.

torching the hose is a BAD thing.