Duckweed Completeformulated by AquaFix
Duckweed Complete
EPA-registered herbicide paired with a biocatalyst for duckweed and watermeal in wastewater lagoons. Case covers roughly five acres of surface treatment.
What it is
Duckweed Complete pairs Flumigard, a US EPA-registered aquatic herbicide, with a biocatalyst that helps it penetrate duckweed's waxy cuticle and then degrades the dead mat. Surface treatment is one pound of herbicide plus one gallon of biocatalyst per acre. It also works on watermeal, filamentous algae and other aquatic weeds.
Buy this when you are seeing
- A duckweed or watermeal blanket covering the cell
- Dissolved oxygen falling under a closed surface mat
- Aquatic weeds that shrug off a plain herbicide
- Sludge and phosphorus spikes after previous weed treatments
How it works
Duckweed and watermeal are protected by a waxy cuticle that sheds a plain herbicide application. The biocatalyst component breaks through that barrier, which is what makes the herbicide responsive rather than partially effective, and it is the reason the two ship together rather than as separate purchases.
The herbicide targets the surface growth, disrupting photosynthesis and reducing plant coverage quickly. That matters in a treatment cell specifically: a complete duckweed blanket blocks the sunlight and surface reaeration a facultative lagoon depends on, and dissolved oxygen falls underneath it.
The biocatalyst then accelerates degradation of the decaying plant material. That prevents the sludge accumulation, phosphorus release and effluent nutrient spikes that otherwise follow a large kill, which is the mechanism behind weed treatments that seem to make the permit numbers worse before they get better.
Check these before you buy
These decide whether this product can work at all. If one fails, fix that first, because the money spent here will not survive it.
- Confirm your state's pesticide permit requirementsFlumigard is a US EPA-registered herbicide. Applications to a permitted lagoon can require Pesticide General Permit coverage, a licensed applicator, or both. The label is law and state rules sit on top of it.
- Read duckweed as a diagnostic firstDuckweed thrives on nutrient-rich, still water. A cell wearing a complete blanket is telling you it is nutrient-heavy and under-mixed. Herbicide clears the mat; aeration and loading control are what stop it returning.
- Plan sectional treatmentA whole-surface kill puts the entire decay load into your treatment train at once. Treat in sections sized to your cells' oxygen budget.
- Schedule around discharge eventsLabels carry discharge and irrigation restrictions, and treating immediately ahead of a discharge is a self-inflicted permit problem.
Is this the right fit
Good fit for
- Duckweed and watermeal in treatment lagoons
- Filamentous algae and other aquatic weeds
- Heavy plant overgrowth in overloaded or poorly circulating cells
- Systems that have seen nutrient spikes after past treatments
Not the answer for
- Fixing the nutrient loading that grows the mat
- Treating a whole loaded cell in a single pass
- Use without confirming your state's applicator requirements
- Cattails and emergent vegetation, which need a different approach
Dosing and application
- Surface application, 1 acre
- 1 lb Flumigard plus 1 gallon PondZilla Pro.
- Surface application, spot treatment
- Quarter acre: 4 oz Flumigard plus 1 quart PondZilla Pro.
- Surface application, 4 acres
- 4 lb Flumigard plus 4 gallons PondZilla Pro.
- Subsurface application
- Higher rates than surface. Quarter acre spot treatment: 1 lb Flumigard plus 1 gallon PondZilla Pro.
- Timing
- Apply during active growth periods. A dormant mat gives the herbicide less to work with.
What to expect, and when
- Before treatingConfirm permit and applicator requirements, decide your section plan, and note current dissolved oxygen so you can watch it through the decay period.
- First daysVisible surface control as coverage reduces. The decay load starts here, which is why sectional treatment matters.
- Following weeksBiological breakdown of the dead mat. Watch dissolved oxygen, particularly pre-dawn, through this window.
- Next seasonRecurrence timing is your loading and mixing diagnostic. Fast return means the underlying conditions were not addressed.
How you prove it worked
Track surface coverage and dissolved oxygen together, because clearing the mat should improve reaeration. The longer-term measure is how long it takes to return, which reads directly on nutrient load and mixing rather than on the treatment.
A duckweed blanket is a process problem before it is an appearance problem. A facultative cell depends on sunlight for algal oxygen and on wind for surface reaeration, and a complete surface mat removes both. Dissolved oxygen falls underneath it, treatment slows, and solids that should be digested settle instead.
Clearing it is worth doing on those grounds. What separates a lagoon treatment from a pond treatment is what happens next: a killed mat sinks, and in a treatment cell it becomes BOD, TSS and a phosphorus release inside your own train. Pairing the herbicide with a biocatalyst that degrades the dead material is how you avoid trading a surface problem for a bottom one.
Read the recurrence honestly. Duckweed cannot establish on moving water, so a cell that grows a blanket every year is telling you something about nutrient load and mixing that no herbicide will change. The vegetation guide covers that diagnostic, and the aeration guide covers the durable fix.
Specifications
| Manufacturer | AquaFix |
|---|---|
| Type | Aquatic herbicide plus biocatalyst |
| Herbicide component | Flumigard, US EPA-registered |
| Targets | Duckweed, watermeal, filamentous algae, aquatic weeds |
| Surface dose | 1 lb Flumigard plus 1 gal PondZilla Pro per acre |
| Case contents | 5 lb Flumigard plus 5 gal PondZilla Pro |
Works alongside
Common questions
How much area does a case cover?
About five acres at the surface application rate of one pound of herbicide plus one gallon of biocatalyst per acre. Subsurface application uses higher rates, so a case covers correspondingly less.
Do I need a permit to apply it?
Often yes. Flumigard is a US EPA-registered herbicide, and applications to a permitted lagoon can require Pesticide General Permit coverage, a licensed applicator, or both. Confirm with your state environmental agency before treating.
Why does it include a biocatalyst?
Two reasons. Duckweed has a waxy cuticle that sheds herbicide, and the biocatalyst helps it penetrate. And the dead mat has to be degraded rather than left to sink, or it becomes sludge, phosphorus release and an effluent nutrient spike inside your own treatment train.
Why does duckweed keep coming back?
Because it is a symptom of nutrient-rich, still water. Duckweed cannot establish on moving water, so persistent recurrence is an aeration and loading diagnostic. Treat the mat with this, then address the conditions or you will be buying it again.
Will it work on cattails?
No. Cattails are emergent vegetation with a rhizome system, and they need either cutting below the waterline or a systemic aquatic herbicide applied in late season. The vegetation guide covers that separately.
Read before you buy
How to Get Rid of Cattails and Duckweed in a Wastewater Lagoon
How to remove cattails and duckweed from a wastewater lagoon the permit-safe way: mechanical, herbicide, and aeration options for treatment cells.
AerationWastewater Lagoon Aeration: The Operator's Complete Guide
How lagoon aeration works, surface vs diffused systems, sizing basics, winter operation, and how to choose the right aerator for your cells.
SludgeLagoon Sludge Removal: Costs, Options, and How to Decide
Dredging vs biological sludge reduction for wastewater lagoons: real cost ranges, how to measure your sludge blanket, and a decision framework.