For some reason every stick that goes into my tank will eventually turn green. I run no GFO, no Carbon, no Skimmer, only live rock. 90 cube with rubbermaid sump. We were moving so there were no water changes for about 4 months. Don't have problems with the actual growth of sps, that seems like its not an issue. I keep seeing Iron, but GFO was removed probably 7-8 months ago. I just picked up a pink milli colony and im sure it will eventually turn green. I run two Hydras over the tank.