Need your help, I do not know what is this red stuff that is growing in my refugium. Is a red cottom like thing, that I do not know if is bad for my tank or not. If it is, how can I control it? (if possible without any chemicals). I also have noticed in a couple of rocks the development of some same color slime that I've tryed to clean taking it out with a squirter. I'm very concern about this, please help.