I am switching a 21 year old whisper flow pump for a new one. The lines in and out are the same...2". I have enough room to cut booth PVC lines...and they seem to line up with the new pump. I have new 2" schedule 80 threaded fittings for the in/out lines. How do I do this without compromising the rest of the plumbing to the filter and heater...how do I glue both fittings at the same time without having to move the existing system?