Hi, thanks, I;m trying to use a 250 to remediate mold in a 1 bdrm today. i have a concentrator, i ended up with a 250p (potentiometer) and am confsed. was that 24 hours on air fed, is it less effective on oxygen fed? when i turn up the pmeter it seems to act like its airfed even though cnneteced to concentrator, as if drawing more air in addition to the supplied ox (produces unbreathable air, just like the commercial air fed i rented once a few months ago) (when lower pmeter level just ozone smell). but theres no pump besides in the concentrator so confused, how it could draw additional.. and while connected. trying to figure out how to effectively use it. Thanks so much!!!