[lostshakerofsalt]

The five to seven minute rule is pretty good. Depending on the water pressure going into the flush connection in my opinion you may get too much water in the tank. I close the dump valve and listen for the sound of the water discharge from the flush tube to go silent. That means that the water level in the tank has risen high enough to cover the flush tube. Then I open the valve. I too repeat the process until the water run clear.