We do have the manuals for all the equipment, but it never mentioned a rinse option and it's not marked on the equipment. The only "sight glass" is a crummy old piece of semi-transparent hose they installed as part of the backwash pipe. I don't think you could really see through it well enough to decide when to stop backwashing. We usually stop when the pressure is back to starting level of 10.

As I said, there is a person coming to give us a regular backwash hose, so maybe that will help us be able to monitor the water that is coming out better. I'm going to ask that person's advice on this problem, too, however I've started to distrust some of the professionals in the pool industry. That's why I am asking here first! Thx...