Hi,
Having just bought a ProQ smoker and had a couple of unsuccessful attempts I turned to this forum for advice and instantly found it. In essence it was a). the quality of the charcoal and b) where to by it! Having been pointed in the direction of the wholesaler Booker, I bought some restaurant grade charcoal - wow! What a difference that makes! Whereas the cheaper DIY store charcoal burnt out within a couple of hours and struggled to maintain temperature, the restaurant grade stuff was hot and burnt consistantly for at least 6 hours.
Well done the Forum!!