It took 1.5 mintues for the pump to drain 3.625" from my sump up to the DT. The sumps internal dimensions are 71*23.25 inches. So that is about 26 gallons in 1.5 minutes, or about 1040 GPH.
The problem is that on start up it almost overflowed before the drains properly kicked in. I had to turn the pump off briefly, 20 seconds, then plugged it in again. It is now running again.
I dialed in the main drain. It took many trips up and down the stairs. It is now dead quiet. Silent. No noise: wife is happier now
So it's running at about 1000GPH, dead quiet, and stays at the same level.
Now I need to re try a power on/off.
I would like to see the flow a little more, but I suppose it is enough as is.
Tom