don't change the screen, it was properly designed ... material doesn't fall down thru the screen, as the air is pumping UP thru the screen ... best to use it as the instructions say - a 'pea-sized' little chunk, and do NOT grind it up ... read the directions ... enjoy your Herbal Aire, it's a quality product, my favorite ... try smoking the leftover 'duff', too ... you usually won't even notice any missing THC ... go figure ... :thumbsup: