Algae is the scourge of outdoor pond owners, and pond algae comes in several nasty types.

Fish ponds can get high concentrations of phosphates from food decomposition, and nitrates from the nitrification cycle. High concentrations of phosphates and nitrates are the food for pond algae, along with some iron as a catalyst.

There have been 2 ways to battle pond algae.

 

"KOI CARE ALGAECIDE" kills all types of algae including string and hair algae!