Hello Paul. We are sorry you experienced this problem. This product does need to be used carefully following label directions for dosage. As algae is treated by an algaecide, it absorbs oxygen so aeration should be increased in a pond that is using an algaecide. In ponds where additional aeration is not an option or water treatments are not wanted to be used, consider using a UV Pond Clarifier. We ask that you call in so we can gather some information and see what went wrong. When calling in please refer to this review. Please contact our Customer Care Team at 1-888-412-6001, Monday – Friday, between 8 AM to 5 PM ET. We hope you give us another chance.
Your TotalPond Water Gardening Specialist, Mary