<a href=showthread.php?s=&postid=7050750#post7050750 target=_blank>Originally posted</a> by jorge
The red tubing with the black valve at the end is indeed the vent valve. When you are filling up the reactor you want to see water coming out of that line to know all air is out, so the tubing allows you to direct the water into the sump or a container and not have water all over the reactor.