Aquatic Herbicide Catalog

Hydrothol Granular Aquatic Algaecide & Herbicide - 20 lbs.

Seed World


Algae can quickly become a major problem for any pond or lake. Not only can it be an eyesore, it can also be detrimental to the health of your water and those who use it. In the United States, algae blooms are the primarily cause of fish kills. Algae can also damage water crafts and boating equipment. If your pond or lake is being overrun with chara, coontail, naiads, hydrilla, mil-foil, star grass, pond weeds, or other algae species, turn to concentrated Hydrothol Granular 191. This easy-to-use formula is also effective for many varieties of lake shore weeds. For over 30 years, Hydrothol has been one of the most trusted and widely-used herbicides/algaecides in America. In fact, it is the only registered organic broad spectrum aquatic algaecide available.

Fast-acting and effective even in slow-moving water, Hydrothol is a versatile choice. And because it will not bind to dissolved sediment, it can even be used in muddy sections of ponds and lakes. It is the premier choice for spot or marginal treatments. Use Hydrothol to clear paths in irrigation or drainage systems. Prepare your waterway for swimmers, skiers, or fishermen.

Feel comfortable knowing Hydrothol is the environmental choice. This granular dissipates quickly and does not bio-accumulate in the hydrosoil or fish. Therefore, when properly used, it will not adversely affect your pond or lake or cause toxicity in fish.

Following treatment, restrict domestic and livestock water usage from 7 - 25 days depending on application. To avoid trapping fish in the treated area, it is best to apply the granular outward from the shoreline or in strips. Apply with a spreader or scoop. See product label for proper application information.

Key Features:

  • 20 lb. Resealable Bag
  • Useful against a wide variety of aquatic algae and weeds
  • Application rates: 3 to 136 lbs. per acre ft. of water
  • Spot treatment rate: 12 lbs. per 1,000 sq. ft. with avg depth of 4 ft.
  • Qualified commercial applicators recommended for large applications

This item cannot be shipped to the following states: CA, CT, NJ, NY, WA, OR, or ME.

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  • K
    KIRK RIPSCH K. R. KIRK R.
    21-02-2024

    HYDROTHOL

    GOT THE 6 BAGS QUICKLY FOR THE BEST PRICE I FOUND / HAVE ORDERED FROM SEED WORLD BEFORE /GREAT COMPANY

  • R
    Rick Gnagy R. G. Rick G.
    19-08-2023

    Clear lake

    First time buyer & will probably buy again. Good price & delivery as advertised

  • C
    Charles Allen C. A. Charles A.
    17-07-2023

    Pond treatment

    Great price fast shipping very friendly emails.

  • g
    george schreiber G. S. george s.
    25-05-2023

    Weed killer

    Great product

  • D
    Darren Russo D. R. Darren R.
    14-04-2023

    Best deal out there!

    Thank you for the fast delivery.

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