This particular tank is new.. about 7 days old.. however, rock, sand, fish is from 2 year tank. I had this problem with my 29 gallon tank so i did a 50% water change plus upgraded to a larger tank (60 gallon).. I know my tank recycled.. i had a diatoms on the sand, but that is clearin up. The tank for 7 days is showing good signs of stabalyzing, coraline algea (small amounts) are on rear glass. I dont want to scrape off the coraline algea but its mixed in with green powder algea on the glass. I posted a thread the other day titled New member which has all my specs on it.. thanks