In my tank I have 2 or 3 pounds of live rock and 20 pounds or so of dry rock that's been cycling for about a month. Maybe more. The 3 pounds of live rock I bought at LFS has dust and dirt particles on it. I moved around some rock today. The live rock was over in the corner of the tank and I wanted to bring it out a little more to maybe filter out these 160ppm nitrates and better cycle the tank. When I moved the live rock, all this dust dirt and debris fumbled off of it and I'm wondering what it is. I dont' have any fish yet. No cuc either. So this dust and debris that came off the live rock... is this beneficial bacteria? Or is is all bad stuff? Algae? It's not on my dry rock, only on the 2 pounds of live rock I got. Is it die off? Did I kill my live rock when I was trying to cycle this tank? :squigglemouth: