I wish I had joined this forum for a better reason but unfortunately I joined it because an aquarium place I went to sold me on getting some of this anti-algae stuff for my full wine barrel fish pond, assuring me it was totally safe for my fish…And it killed every single one of them within 24 hours. My fish were big and actually friendly and I’m totally heartbroken. Based on some of the other posts I have seen I should have let nature take its course, I did have some water hyacinth growing on the surface but they froze and I pulled them out and threw them away, I think that’s where the problem started because the algae got out of control as soon as there was nothing covering the barrel. Anyways, I’m just sad, but when I get my barrel back up and running with healthy bacteria and plants I’ll be looking for your experiences.