btbubba- You have to glue it together if it has to hold pressurized air. If you are using it to just encase and protect an inner airline then glueing is not necesssary.
I have never used pvc pipe as an underground airline but it has and it can be done. I have always used the black polylethylene water pipe; primarily since it is cheaper.
When using the pvc pipe, I prefer to use the white pvc vs the cream colored pvc. If using white pvc they make a glueable end coupling for the pvc that is either 1. female to slip over the pvc pipe with other end female threaded (female adaptor-SLIP xFNPT) or 2. female slip for pipe and other end is male threaded (male adaptor- MNPTx SLIP). There are then fittings (usually gray color)with 1a one female threaded end and other end is a hose barb or 2a male threaded and other end hose barb. Screw appropriate one in the fitting that you have glued onto the pvc; slip your underwater airline onto the hose barb. Parts 1 and 2a should be the easiest to find in Home Depot or Lowes. Part 1a is often hard to find at most stores. NOTE the hose barbs are most commonly stamped w/ 1/2" which is truly a 5/8" hose diameter. However the 1/2" black poly fits these 1/2" hose adaptors (5/8" garden hose also fits these 1/2" hose adaptors). It sounds confusing and it is, the plumbing industry has mixed sizes for different styles of pipe. Make sure the fittings will match your airline. Take a piece of airline with you when shopping for parts.
