I constructed a running water gravity bong out of a 5 gallon jug, added a waterhose faucet for the release, and 5 pipes/hoses all with shut off valves, and a socket for the bowl. We call it "Satan's lung",

saves a lot of smoke. You have to start hitting while it's filling though or the smoke gets stale, usually takes about 45 minutes to clear completely, which is a bunch of THC-less remains near the end, but it gives us a challenge when we're high. Hell, it may be less than 45, you know how it is after a few hits, lol