I want to replumb my equipment on my 24' above ground pool to 2" pvc. I was planning on using pump unions (are they 2 or 2 1/2 inch?) on the equipment, only problem is the filter has the male external threads on the return and waste ports but only 1.5 inch female internal threads on the pump port. One of the attached images shows a fitting on that port with the pump union threaded to that but I can not seem to figure out what adapter that is. Or am I thinking it wrong and don't want to use pump unions at all of the equipment fittings?