Dan - a more natural and longer lasting solution for your green water situation would be to add some small rotifers to your tank. They will establish a population in your tank with resting cysts in the gravel that will keep green-water in check. I believe that one of reasons some people have green water problems while others do not (even with lousy water quality) lies with the microscopic populations in their tank. Just make sure your not using both a DE/micron filter and Rotifers - the filters will strip them from the water column. You can order rotifers from numerous on-line sources or if your brave they can be gathered naturally from the debris in roof drain-pipes (soak for while with water and then filter through some pantyhose to remove the debris) Dave Walburger -----Original Message----- From: Simon, Dan [mailto:dan.simon@pcgw.claircom.com] Sent: Tuesday, December 05, 2000 8:34 AM To: 'GSAS Mailing' Subject: In need of UV All, Help. I am temporarily in need of a UV sterilizer to combat a green water issue. If someone has one to loan for a week (or so), I will return the favor with some of the best Rainbowfish you've ever seen. Thanks, Dan Simon 206-369-0045