Yes... use a filter.... I have heard both stories as well..... but I would lean MUCH more towards the hose breaking down and contaminating the heater... because with all of the LP furnaces and boilers and such out there.... and NONE of them have filters on them that use bulk LP... and the regulators would plug up for sure if it was the LP... so I would lean towards the hose being the culprit. I believe there is a green hose that Mr Heater sells that does not need a filter, however... maybe e-mail them and check it out...