Blue-green algae (cyanobacteria) love warm, still, nutrient-rich water. In Queensland, blooms can appear suddenly and create health risks for livestock, pets, and people, while turning clean water into a green, odorous mess. Here’s how to identify, treat, and prevent blooms—plus the best products and services to keep your dam safe and clear.

What Is Blue-Green Algae? (Cyanobacteria 101)

Blue-green algae are photosynthetic bacteria that multiply rapidly when conditions are right. Blooms often look like pea soup, streaks/paint-like scums, or blue-green surface films. Some species can produce toxins (cyanotoxins) that irritate skin and may harm animals if ingested. If you suspect a toxic bloom, keep people and animals away and start control actions promptly.

Causes & Effects of Blue-Green Algae Blooms

• Excess nutrients (fertiliser runoff, manure, decaying organics)
• Warm temperatures & high light (spring–autumn, shallow zones)
• Low circulation / stratified water (little wind or no aeration)
• Turbidity (suspended clay/silt can carry nutrients)

Effective management tackles symptoms now and root causes long-term (nutrients, light, stagnation). Our curated Pond Algae Control and Blue-Green Algae ranges address both.

Manual Removal Methods (First Response)

Before you treat chemically, remove as much biomass as you can—this reduces oxygen crashes and improves treatment efficiency. Use wide-mouth rakes and skimmers to take out thick mats/rafts around edges and windrows:

• Aquatic Weed Rake or the Razer & Rake combo for heavy lift-outs.

Treatment Using Aquatic Herbicides & Algaecides

For active blooms, select a treatment that suits your water use and species present. Observe label directions and withholding periods (stock watering, irrigation, recreation).

• Copper Sulphate Aquatic Algaecide — widely used for blue-green algae and filamentous algae; apply early in sunny conditions and remove larger mats first.
• REGEN – Alguard (reduced-copper liquid) — controls a range of planktonic/filamentous algae with up to 80% less copper than conventional copper algaecides.
• REGEN – Algaemaster (granular oxidising) — destroys algae on contact and releases oxygen as it dissolves.

Not comfortable treating yourself? Book our professional Aquatic Herbicide Spraying service for correct product selection, dosing, and compliance.

Best Products to Control Blue-Green Algae

Algae Removal Tools (Support & Clean-Up)

• Aquatic Weed Rake and Razer & Rake combo — speed up biomass removal pre-treatment and during clean-ups. See all Cleaning Tools.

Use of Aerators & Fountains (Circulation & Oxygen)

Increasing dissolved oxygen and breaking up stratification reduces conditions that favour cyanobacteria:

• Explore Dam Aeration systems, or go turnkey with the Evolution 1/2HP Surface Aerator, SPLASH 2008 Aerator, or Sprint 1.5HP fountain.

Light & Nutrient Management (Prevention Allies)

• Pond Dyes: Reduce light penetration to slow algal photosynthesis — Aquatic Blue or Regen-Blue Liquid; also see Pond & Lake Dyes category.
• Flocculants: Drop suspended clay/silt (and attached nutrients) — Aquatic Clear Dam, Aquatic Clear Drop Granular or Block.
• Beneficial Bacteria & Natural Aids: Aquatic Waterbac and Barley Straw Bales compete for nutrients and improve clarity/odour. Bundle option: Waterbac + Barley Straw. See all Water Clarity.

Preventative Measures & Maintenance (QLD-Ready Plan)

• Reduce runoff & nutrients: Fence stock from banks, plant vegetated buffer strips, and manage fertiliser near water.
• Keep water moving: Install aeration; clean filters; remove decaying matter promptly. See Dam Aeration and Pond Fountains.
• Monitor clarity: If water clouds after rain, treat turbidity with flocculants to cut nutrient availability.
• Schedule maintenance: Combine periodic skimming, bacteria dosing (e.g., Waterbac), and dye top-ups (Aquatic Blue) through spring–autumn.
• Need a hand? We can assess, treat, and maintain your dam. Start with Manual Removal or Aquatic Herbicide Spraying, or Contact us for a tailored plan.