Hydrothol Granular Aquatic Herbicide & Algaecide 20 lb
Cannot be shipped to AK, CA, CT, DC, DE, HI, MA, ME, NJ, NY, RI, VT, WA

Hydrothol Granular Aquatic Herbicide AND Algaecide

Hydrothol Granular acts as both an herbicide and algaecide, making it an excellent choice for pond owners. Hydrothol reacts quickly once applied to ponds with actively growing algae and weeds. 

Treats up to 10,000 sq ft

Active Ingredient: Mono Salt of Endothall 11.2%

What does Hydrothol granular kill?

Planktonic algae (green water algae)

Filamentous algae (string algae, pond scum)

Branched algae (chara, nitella)



American Pondweed

Curly Leaf Pondweed

Sago Pondweed





Should NOT be used in ornamental ponds, or ponds with Koi or Goldfish.

Applying Hydrothol Granular

Apply granular herbicide in areas with active weed/algae growth with a gloved hand or granular hand spreader.

Hydrothol Application Rates

Treatment Area (with avg depth of 5') Managing String Algae Managing Chara & Nitella Managing Submerged Weeds
1,000 sq ft 2 lb 4 lb 4 lb
10,000 sq ft 20 lb 40 lb 40 lb
40,000 sq ft 80 lb 160 lb 160 lb

*See product label for additional dosage rates for ponds with flowing water

Full Hydrothol Label and Instructions

Hydrothol SDS (MSDS)

When is the best time to apply Hydrothol?

It is best to treat with Hydrothol early in the season when weeds/algae begin actively growing. 

Aquathol Super K vs Hydrothol Granular 

Hydrothol Granular and Aquathol Super K are both granular aquatic herbicides. Aquathol targets pond weeds. Hydrothol targets pond weeds and algae.

Aquathol has no water use restrictions. Hydrothol can be toxic if applied at a stronger rate than recommended on the product label. Only treat 10% of surface area at one time with Hydrothol to limit the risk of toxicity to fish and invertebrates.


Cannot be shipped to AK, CA, CT, DC, DE, HI, MA, ME, NJ, NY,  RI, VT, WA


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