I have a one acre pond with Fhm and GSH I stocked Rbt to have something to feed and watch the water is very clear but slowly starting to get a bloom. I built what I think of Fhm breeding hotels it is plastic(cardboard) cut into 8x8" squares and stacked on four pieces of quarter inch all thread with about two inches between layers(six layers) and stick the ends of the rods into the bottom in the appropriate depth. I placed several next to a retaining wall that is by my front porch so I can sit in my reclining chair and watch the action they seem to be working great I see males setting up on each layer and I can place them about twelve inches apart and they seem to work their specific layer without trying to chase others off