Hard pipe. Need help with gate valve.

[Countpyro1]

My waterway pump has a gate valve that has a air line off on it going into the pump strainer basket feeding from the skimmer. It has a straight end on it to pipe clamp a hose on it. I want to hard pipe the lines and there is a valve-air like valve on the bottom that isn't attached to anything? Does this allow a small amount of air to flow in the pump? Was something suppose
to be attached? I was gonna grab a new union and not use this piece. Is this okay or do I need that piece because of the bottom valve thing

 

[Countpyro1]

So I found on there website:

• 3/8″ barbed fitting to accommodate offline chlorinators

weird this would be before the filter as I thought it should be after. Im assuming I don't have to worry about this nipple and just replace the hole piece.

 

[pooldv]

Correct, that should have been plumbed after the filter.