hi all i used my wfp for the first time today on a conservatory roof, i said id pop back and see how it turned out. well i must say it was terrible, ive said ill re do it when i come back off my hols. obviously im not using it righty im thinking of paying £95 to go on the course with ionics, what do you all think ?. Also how long does the purified water last in the butt or canisters, before its no good ?.