Since I've been running the IM reactor with gfo inside it, my corals, especially sps, have been coloring up and growing very well. My cheato doesn't seem to be growing much, but it's not dying neither. I'm thinking of getting another IM reactor to tumble carbon in it vs just placing a bag of it in the sump. I like these reactors because they don't take up much space, and you can control the tumble/flow with just the twist of the knob. I never have to worry about zero phosphates, because I feed heavily and dose acropower.