| It's really very difficult to assess what a problem might be without knowing the water chemistry. You will need to get yourself a good test kit or at the very least, take a water sample to a pond store so they can test it. Algae needs nutrients to thrive, so you need to determine where it's getting it's nutrients. Excess koi food, excess fish poop (caused by too many fish), build-up of crud in the pond bottom, and improper filtration are all likely contributors. Sand filters are typically not very good for water gardens. Sand filters were designed to filter chemically clean water (swimming pools) and simply cannot handle a large load. The sand clogs up and develops channels through it which allows the water to pass with no filtration. Most people who have sand filters have to back-wash them at least once a day, sometimes even more! |