Pond algae problems are typically caused by an excess of nutrients in the water, not enough aquatic pond plants in the system and too much direct sunlight. If you can create a proper balanced ecosystem in your pond, algae can be managed. You will never be able to get rid of pond algae 100%, and the truth is that you really don’t want to. Believe it or not, algae is normal part of all aquatic ecosystems. It can however be controlled and managed.
The two main types of koi pond algae that gives pond owners trouble is green water that is similar to pea soup and string algae which occurs mostly in the waterfall and stream portion of the water feature. With the proper pond filters and excellent algae management techniques, both types can be a thing of the past.