I should start by saying that this works in properly maintained water gardens. If you refer to your water garden as fish pond or koi pond that is the first signal you might lean more on the fish and less on the garden. In the spring remember not to begin feeding your fish until your plants are well established. You can throw off the balanced ecosystem with a single feeding and can cause some damage to fish if its real early. After winter a fish’s stomach is a little fragile. It has not had a good amount of food in many months perhaps, floating pellets or other fish-foods can cause a fish’s stomach to swell and lead to bleeding & even death. You want to introduce feeding slowly (but that’s more for a blogging fish day, you want to know about the Iris’s secret to preventing the spring algae bloom. Iris are one of the first plants to come alive in the pond, perhaps the very first. This plant and Marsh marigolds can suck the excess nutrients out of the pond beginning around the time of the final few frosts. Having a few areas of iris can dramatically reduces nitrites in the water and begin the process of cleaning the pond months before hyacinths or other plants can begin filtering the water. Iris also add a nice spring flower when hardy lilies are just beginning to send up leaves. In the spring, if you have a few areas of established iris (Flag Iris, Japanese Iris, Louisiana Iris are all partially aquatic and can handle a couple inches of water), dont feed the fish, and do not have dead leaves and debris in the pond the chances of a spring algae bloom or green water are greatly reduced. A good water garden is a biologically correct water garden.