I am going to plumb in my new filter+pump tomorrow. I've got pretty much all of it dry fitted so all that's left is the welding.

I've done simple drain lines for home plumbing only and have never actually welded this many PVC joints before (estimate ~50).

With many valves, unions, elbows... in tight quarters, I'm wondering what the best plan of attack is...
  • Weld away from the pump+filter or weld in place?
  • how long to wait for each joint to set before welding on another piece (this could take some time if I have to wait 15 minutes between each weld).
  • best approach to get the unions + valves to line up (straight line marked with a sharpie?)
Any advice?