<a href=showthread.php?s=&postid=12477202#post12477202 target=_blank>Originally posted</a> by compulou
It wouldn't drain any more or less water in volume/gph, it just doesn't allow ALL the water to drain out of that section. Honestly if the system has a large volume of water the amount you leave in there really wouldn't matter. If the system is a smaller system I guess it could make a small difference.
I guess what I'm trying to say is the whole point of adding the tube is; Pump stops, less water drains into the sump. And that's always a good thing.