Try adding a little iron. I use a capful of Flourish every month. Many on here have found that they have to do this to keep it growing. BTW my tank was covered with those dusters. I added a CBB and all and I mean thousands were gone in a week! They are still in my sump but I don't see any harm.sKuLLy said:I'm trying to figure out why my refugium plants don't grow well anymore? I was wondering if because I have so many dusters in the refugium if they are taking the nutrieants away from the plants? I keep my 100w light running 24hrs??