I have never used the product, but I feel safe is stating that at the very least you need to rearrange the flow in your tank or (more likely) you need more flow in your tank.
Do a search, using the search function on the tool bar on MR, and you'll find a lot about Ultralife Red Slime remover as well as Chemi-Clean. You'll find info on Cyano/red Slime too.