Ive never used this product (or any similar ones for that matter) but have heard that some of them are better than others. Of course, all of them offer a remedy but none are really a solution. In other words, they may get rid of your current algae but they do not really work to eliminate the initial cause(s). The best thing to do if you use a product like this is to also determine what is causing the algae in the first place, and then fix that as well. I don't like adding any extra chemicals (ie, any other than decholinator) to my water unless I absolutely need to. I don't know what, if any, long term effects these products may have in fish if you come to relyt on them to solve the algae problem.
\Dan