One of the most important items that people leave out of their post is water quality information. Other parameters such as nitrate levels, and any others you test kit can do, would help, too. If you do not have a test kit, get one. You will be asked about those readings. If you don't have all that information or the time to read the main web site, but do have a problem that you need help with and need it right away, post as all the info you DO have.
Any solution given without most of the above information in mind is just a guess and no more.
Now, I feel better. That certainly was NOT my intention. Introduction to the video. Get an AquaDyne. It's truly excellent in many ways.