Agree with what the pp said. When I took my son to the ENT (ear, nose and throat) doc, he said the mucous is the body’s reaction to the reflux. The mucous acts as a protective barrier. It keeps the airways from getting too damaged from the acid.
Agree with not suctioning too much. These lovely ladies gave me that tip. I suction my son only at night, just so he sleeps better. The rest of the time, I spray saline in his nose and let gravity do it’s thing. Agree that the wedge helps. I got mine from amazon.com, but you can find the same one’s at Babies R Us.