Pond Algae Control: Causes, Identification & Effective Treatment

Algae blooms are the #1 pond headache. Left unchecked, they clog pumps, choke plants, ruin water quality, and turn your feature into a green mess.

What Causes Algae?

• Excess sunlight (no shade)
• Nutrient overload: fish waste, fertilizer runoff, decaying leaves
• Tap water (contains phosphates/nitrates)

Common Types

• Green water ("pea soup"): Free-floating microscopic algae.
• String/blanket algae: Hair-like mats on surface or submerged.
• Floating scum: Green films or clumps.

Chemical Treatments

• Diquat (Weedtrine-D): Contact herbicide for submerged growth. Best combined with copper or endothall.
• Chelated Copper (Cutrine Plus): Stable, effective contact algaecide.
• Copper Sulfate: Budget option; less effective in high-alkalinity water.
• Endothall (Hydrothol/Aquathol): Granular contact herbicide. Apply in spring at peak growth.

Match treatment to algae type. Combine with shade, nutrient reduction, and beneficial bacteria for lasting control.