Just letting everyone that I know and can reach, not to use the Hydra Quartz product that has been making a sweep through the US. I used it several weeks ago and it killed every fish that I had in my pond(15-20). In dealing with HydraUSA which is really a company in England I've found no satisfaction with their attempt to explain to me what might have happen. I was skeptical and took every precaution that I could following the directions exactly as written with the exception of dousage and with that I cut back from the recommended amount. Needless to say it was devistating to lose all my fish and I want to protect others from the same horror.