Scored a free heavy duty carbon filter housing the other day. Looks like it should hold about 1.5 quarts of liquid. All I need is some pipe fittings and a screen tto convert it to a hopback. My setup is geared towards 5 gal batches and is a simple gravity feed system. I have no desire to go any bigger or make the setup more complex. Think the hopback would work without a pump... a simple gravity feed with enough head?