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Worried your “green scum” could be cyanobacteria?

Cyanobacteria can produce toxins that threaten people, pets, and wildlife—and you can’t confirm it by sight. Act smart: keep pets away, reduce nutrients, and send a sample for FREE lab screening.

Get Free Screening Request Free Print Catalog What to Look For
Why this matters

Cyanobacteria risks—fast facts

  • Toxins can harm people, pets, livestock, and wildlife—even small exposures can be serious.
  • Looks can deceive: cyanobacteria can mimic harmless algae; microscopy confirms the difference.
  • Dried scums can stay risky: toxins may persist on the shoreline and re-enter the water.
  • Treatment timing matters: killing an active bloom can release toxins—start prevention while you wait for lab results.
Step 1

What to look for (submit a sample to confirm)

Microcystis floating surface scum resembling green paint or powdery film on calm water
Microcystis — floating surface scum that resembles “green paint” or powdery film on calm water.

“Green paint” slicks / powdery film (surface)

Forms floating surface scums; common in warm, nutrient-rich, calm water and collects along leeward shores.

Oscillatoria dark, slimy bottom mats with long hair-like strands that can detach and float
Oscillatoria — dark, slimy bottom mats with long hair-like strands; mats may detach, float, and drift.

Dark benthic mats / hair-like strands

Grows as cohesive bottom mats; gas-lifted clumps can surface and drift to windward banks.

Nostoc forming gelatinous green blobs or cushions in shallow, calm areas near shore
Nostoc — gelatinous, jelly-like colonies forming green blobs in shallow, calm areas near shore.

Jelly-like green blobs

Gel colonies in quiet shallows; feels slippery/jelly-like and may expand after rains.

Lyngbya dense, tough, fibrous bottom mat that is dark green to black and tears into clumps
Lyngbya (Microseira wollei) — dense, tough, fibrous bottom mats, dark green to black; break free and drift.

Dense, tough bottom mats (often very dark)

Thick, hair-like mats on the bottom; rubbery clumps can tear loose and collect in coves.

Only microscopy confirms cyanobacteria—submit a sample to be sure.
Step 2

Safe preventive steps (to start now)

  • Keep people & pets away from suspect water and shorelines.
  • Run or install aeration to boost oxygen and circulation.
  • Shade the water with pond dye to limit sunlight that fuels growth.
  • Cut phosphorus — bind phosphate now to remove a key algae food source.
  • Add beneficial bacteria to digest organics and consume excess nutrients.
  • Document conditions — photos, wind, and weather notes help tailor a plan.

Pond Dye

Blocks problem light wavelengths; fish-safe when used as directed.

Shop Dye

Phosphate Binder (MetaFloc)

Biological clarifier that permanently binds phosphorus; improves clarity.

Shop MetaFloc

Beneficial Bacteria

Reduces nutrients and odors; works best with aeration.

Shop Bacteria

Aeration

Increases dissolved oxygen and circulation; supports overall pond health.

See Aerators
Lead option #1

Free Cyanobacteria Screening — simple & expert-reviewed

  1. Add to cart and finish checkout to get the sampling PDF instantly.
  2. Collect & ship your sample as instructed.
  3. Lab tech review — you’ll receive results with next steps.
Tip: Need immediate insight? Consider the Cyanotoxin Test Kit (microcystin + anatoxin) while your sample is in transit.
Lead option #2

Free Pond & Lake Management Catalog (print)

Get our mailed catalog with treatment guides, ID tips, and planning checklists—great to keep at the dock or barn.

Request Free Print Catalog
FAQ

Common questions

Can I confirm cyanobacteria by sight?
No. Visual cues help you flag risk, but only microscope analysis confirms cyanobacteria. That’s what the free screening is for.
Is it safe to treat a visible scum immediately?
Killing an active bloom can release toxins as cells rupture. Start prevention first (aeration, dye, MetaFloc, beneficial bacteria) and wait for results—or use the 30-minute cyanotoxin test kit.
Will pond dye or bacteria harm fish?
Natural Waterscapes’ pond dyes and beneficial bacteria are safe for fish and wildlife when used as directed.
Where do I start if I’m overwhelmed?
Submit the free screening and request the free print catalog. You’ll have expert-reviewed results and a handy guide to plan next steps.
Free Screening Free Catalog