an amusing side-note (now) is that I mapped this all out before installation and then found that the Whale 3-way valve had to be inverted to fit under the locker lid. Unfortunately, I did not cipher this into the final evacuation equation. On our first pump out (no I didn't test it in advance - I had installed it myself and knew it to be perfect ). So, when I began pumping the first time there was an inordinate amount of resistance on the old pump handle - sure enough I was trying to pump out through the sealed deck fitting which of course was impossible - it did show me where the weak spots in the hose joints were though ...and also alerted me to the fact that the expensive Swedish hose clamps would have been money well spent (you can really crank 'em down - they were added at the next port of call). The clear plastic vent tube was later replaced with something a bit more appropriate as well.