I have 3 "normal" returns (just straight pipe through the plaster) and another "return" for the automatic vac./cleaner. I have rubber plugs that fit the 3, but the vac return has a twist lock type connection to it, and doesn't appear that it would accept any of the plugs I have. Do I treat it like the main drain and just use the valves to cut it off once I'm blowing air out or should I have some sort of cap/plug that fits it?
TIA
TIA