going by the instructions and the pictures with the adapter i have given up on trying to bleed the system..... if the res is below 85 percent the pumps suck on air..... you can only fill it to about 90% just how the holes are cut.... turning on the pumps causes the water line to drop below 85% and it sucks air you try try to add more water but it just doesn't seem to help. why would you design it to use the top most hole in the res when using 2 pumps in a series???