I have a recent explosion of this algae (please see photos). one of the pics is my GSP, and the other is of a turbo snail believe it or not. I tested Phosphates and they are around 0ppm ( my test kit is only in .25 ppm increments currently. I try not to overfeed, weekly water changes etc. its in a 5 gal pico, with a Fluval Nano Marine light. Inhabitants are 1 tiny fire fish, 2 small hermits, 2 nass snails, and 1 turbo. I use RODI water for topoffs and salt mix... I'm using a recommended schedule for the light (slowly ramps up), but not sure if I have two much of a light schedule.