United Phosphorus Inc Hydrothol Aquatic Herbicide 20 lb Bag — Endothall 11% granular for spot aquatic weed & algae control

Hydrothol Aquatic Herbicide is an 11% endothall granular formulation designed to control algae and nuisance aquatic plants in lakes, ponds, canals and marginal zones.

This granular Hydrothol (Endothall 11.2% mono salt) in a 20-pound bag is formulated for targeted aquatic weed and algal control where spot or sectional treatments are needed. Because the product acts rapidly and dissipates quickly, it is used by public works, pond managers and commercial applicators to reopen recreational access, manage noxious weeds and reduce problematic algal growth. Always follow label directions and local permitting requirements before applying; liquid forms exist but are restricted to licensed commercial operators in many jurisdictions.

How quickly does Hydrothol work and how long does it persist?

Hydrothol begins affecting susceptible algae and plants soon after proper application, with visible decline often within days under active growth conditions. Its environmental persistence is short; Hydrothol breaks down rapidly in water and sediment, helping limit long-term residues.

• Visible control commonly appears within several days of treatment.
• Reported environmental half-life typically under seven days when used as directed.
• Does not tend to bioaccumulate in fish or bottom sediments.

Where is Hydrothol best applied and how should treatments be targeted?

Hydrothol is most effective for spot, marginal or sectional treatments in slow-moving waters such as ponds, lakes, drainage ditches and irrigation canals. Because treatments can affect fish if misapplied, applications are commonly made from the shoreline outward or in strips to avoid trapping aquatic life.

• Ideal for shoreline, nuisance weed beds and localized algal blooms.
• Suitable for muddy or murky water because it remains active despite suspended sediments.
• Use sectional or spot treatments rather than whole-lake applications unless under a qualified applicator's direction.

What safety and regulatory considerations should I know before using Hydrothol?

Hydrothol must be used in accordance with the product label and local regulations; in many areas permits or certified applicator status are required for aquatic herbicide applications. Proper application patterns and rates reduce risk to fish and non-target organisms and help ensure environmentally responsible control.

• Check and comply with local permitting and label requirements before treating.
• Only marginal or sectional treatments are normally recommended to minimize ecological impact.
• Applications should be planned to avoid trapping fish in treated zones.

Which types of algae and aquatic plants does Hydrothol control effectively?

Hydrothol is a broad-spectrum organic aquatic algaecide historically used against a wide range of filamentous and planktonic algae and many nuisance submerged and emergent weeds. Efficacy can vary by species, strain and environmental conditions, so scouting and correct timing during active plant growth improve results.

• Commonly applied against filamentous algae and dense surface mats.
• Also used for control of select submerged and marginal weeds when applied properly.
• Performance depends on species susceptibility and environmental factors.

Who this is for: Hydrothol 20# granular is intended for pond managers, municipal and irrigation districts, landscapers servicing water features, and licensed commercial applicators who need a targeted, short‑lived herbicide/algaecide option. It is suited to situations requiring quick control of nuisance algae and weeds without long-lasting residues, provided label directions and local regulations are followed.