And a bit in my main tank. It began about 3 weeks ago and has slowly progressed. I had 2 jawfish die a little over a month ago and that's when I began to notice the build up. Since the jawfish died in their holes I could not get them out. The cyano began to build around their hole and then disapeared for about a week. Now it's back. It's in my sump in the Caulerpa, and in some of the substrate in the main tank(I have about a 4" DSB). Also I have noticed a build up of bubbles comming from the inlet into the main system. I really don't understand what is going on. Water tests indicate that all levels are at zero. PH around 8.3. I am doing weekly water changes. I haven't had a problem like this on this before. Does anyone have any advice on this. The LFS reccomended I use a Red Sea slime remover but I'm leery of putting that into my tank. I thought I would consult this board first. Any info would be great.