People are often mystified as to why algae appears in their pond. There is no mystery! Algae whether it be string algae or the algae that causes the murky green water is caused by only one thing. An excess of nutrients in the water ---the mystery is?..where do these nutrients come from?
These nutrients can come from a number of sources: Nutrients come from both organic and inorganic compounds. The organic sources are leftover fish good, fish waste, decaying plant parts and pollen. Inorganic sources come from minerals present in the tap water and dust.
You can no more keep nutrients out of your pond than you can keep algae from growing in it! So what's the secret? Without a filter the answer is lots of plants and just a few fish. Plants compete with algae for nutrients, the only time algae can get the upper hand is in the spring or fall when plants are dormant and the temperatures are still warm. This is why you often experience green water and string algae in the early spring and late fall. Plants alone can keep a pond clear in the summertime, as long as you don't have a huge fish population. In the spring and fall you can control algae blooms with several different products that are safe for your plants and fish.
