After determining I had over 6" fall from the sepeptic tank out fall to the turning structure out let, I added the up turned 90 bend on the the out going pipe. This then raised the level of the effluent - but not enough to back all the way to the tank. This raised the level in the structure by 6"s. It also added the volume of effluent in the submerged pipe to the aeration process. I believe some bubbles will travel up the submerged pipe aiding in circulation.