I'm plumbing my tank and I'm trying to figure out Unions. I'm going to glue PVC to the slip bulkheads on the underside of my Eshopps Eclipse L overflow tank. That part scares me a bit because it's permanently connected to the expensive overflow box. Any alternatives? The main question I have is what kind of unions should I use? Should I use slip x slip or thread x thread or slip x thread? I was thinking (thread x thread) so I can easily remove them and fix whatever mistakes I'm sure I'll make since this is my first build. Thanks!