AT 300-400 an ounce why would anyone want to suck half their unburned weed into the rancid bong water. A screen keeps the water much cleaner and allows for complete combustion. Cleaning the screen every 4 or 5 bowls is a small price to pay for a clean bong. Then just a clean water change every few bowls keeps you smoking smooth without big chunks of ash floating in the water and later sticking to the sides of the bong when it is emptied.