So here is an update, and things are looking really good!! The first few pics are the concentrator I made. It worked really well! The others are what left and some of what is gone. I would say 80% of the algae is gone. In all honesty there is only one part that I'm worried about. There is a piece on the edge of my green monti. I wasn't sure if I could spray that directly or if I should just clip off the edge of the monti. In terms of coral death due to GHA, the monti's are the only things that suffered. Very very pleased!