I keep learning things about plumbing that I really should have known in the first place. The most recent is that my drain line which is cheap 1/2″ unreinforced flexible tubing from HD, collapses over time. The problem is that with 10ft of static drop to the sump pit plus whatever momentum the water obtains while draining, the line is subjected to a lot of negative pressure when the drain line is closed. Works fine at the start but it gradually collapses the soft line. The result is a slower and slower drain process as the line gets smaller.
I’m going to try some 1/2″ PEX tubing next. It is inexpensive, flexible enough for the run to the pit yet has a relatively hard wall which should hold it’s shape fine over time. PEX is increasingly used to plumb hot and cold water in place of copper or CPVC.
Now I get to demonstrate plumbing incompetence with a whole new set of fittings!