Could have been change in flow but I'm leaning towards change in surface movement that allowed more intense light to get to shroom and agitate it.
I'm finding out it changes the entire par game when you have minimal surface movement. Where others may be able to push envelope because of heavy top movement and corals getting a break from constant direct intense light as opposed to light getting broken up and deflected so its not giving them a sun burn and cooking them I guess.
Probably will have to move it a bit lower if you plan on removing wave maker.