Hi, I bought an NS 36 replacement filter for my Pentair DE stainless steel pool filter off amazon. When it shipped I got a new filter that looked like the one I'm going to replae but also a tube that I haven't seen before. It looks like this.
There is no obvious place to put it on the new filter assembly and I don't remember seeing anything like it in the old filter. Its an airbleed tube from what I can tell but there is no instructions or videos I can find of how or where to install it.