Hello, I am new to this site but I wanted to share my experience. I have a 180g mixed reef with a refugium that has been up for about a year. I upgraded from a 75g. So, I started having a fuzzy algae growing like a blanket across my sand bed. No problem, I just siphoned it off. But within days it would return. My nitrates are zero as well as my phos, I even tested my RO/DI water. I run the outer orbit fixture which consists of 3-250w metal halides 14k phoenix, and 8 actinic t-5's, and your standard moon lights at night. I had replaced all bulbs in the beginning. Recently, I noticed a few patches of hair algae and what l assume to be dino starting, along with some orange algae in places on certain rocks. I continuously remove the algae manually as much as i can, wet skim, freq water changes, moving my powerheads, etc. My tangs, angel, snails, etc will not touch any of it. The main one I didn't care for was the one on the sand bed. So I decided to change out the sand, which I did, but only in the front as a test. Within 4 days, the fuzzy mat was back! That's when I came across this thread. Many thanks to you all for posting on here. I decided to try this stuff. First dose went in on Wednesday. Within 24hrs, the sand bed looked much better, but is not totally clean. Some algae was noticeably floating in the water column. The dino is unchanged,(from what I can see) but it is towards the back of the tank, and I will siphon it out today with my water change. Next dose is due on Saturday. I am amazed at what it has done so far on my sand. I was really about to tear this tank down. No negative affect on fish, snails, or shrimp. Some zoas (mainly the blue hornets) closed up, and my acans retracted some but no deaths. Sorry for the long post. Just wanted to share.