Hydrothol 191 Granular Aquatic Herbicide


Our Best Selling Granular Aquatic Herbicide
Kills Most Lake Weeds and Algae!

SKU: HHYD1 Categories: ,


Hydrothol 191 Granular Aquatic Herbicide/Algaecide is the most versatile granular product ever! It is excellent for use in spot treatment due to its wide range of herbicidal activity on most aquatic species and also very effectively kills Chara too.

Hydrothol 191 Algaecide/Herbicide effectively kills most pondweeds, naiads, milfoils, coontail, stargrass, hydrilla, canada waterweed, planktonic algae, filamentous algae, and chara. Hydrothol is the perfect choice for lakeshore weed & algae control.

Due to the fast activity of Hydrothol, it can be effectively used in slow moving water, such as drainage and irrigation canals. Hydrothol is also effective in muddy or murky water because it does not bind to the suspended sediment or organic matter.

Hydrothol is the only registered broad spectrum organic aquatic algaecide available today. It can be used in combination, in rotation or as an alternative to copper for control of algae.

Application Rates:

Application rates vary depending upon depth and plant types.

For most submersed weed applications 10 lbs will treat 2,000 square feet.

For example:
A 2 acre pond that averages 4 feet deep would be a total of 8 acre feet. You would need 24 lbs of Hydrothol 191 to treat the vegetation in the whole pond.

A patch of mixed aquatic vegetation along a shoreline that goes out 20 feet and is 100 feet long would be 2,000 square feet. You would need to apply 10 lbs of Hydrothol 191 to effectively treat this patch.

Application Tips:
How to apply Hydrothol 191?

Just simply broadcast Hydrothol 191 with a hand scoop or a spreader directly onto the vegetation. Always try to calculate the square footage of the treatment area so you can use the correct amount of Hydrothol within that area. Doing this will save quite a bit of product waste and overuse.

For best results, apply Hydrothol early in the plants life cycle while it is still actively growing to provide season long control. During the summer I would recommend not treating more than 1/3 of a pond at a time.

Water Use Restrictions:

Hydrothol is very safe for fish if used properly. There is a 3 day fish consumption restriction, 7-25 day irrigating and livestock restriction depending on the dosage following the application of Hydrothol 191.


Read and follow all local, state and federal regulations pertaining to the use and application of these products before ordering.



– California
– Connecticut
– Massachusetts
– New Hampshire
– New Jersey
– New York
– Oregon
– Rhode Island
– Washington State
– Vermont

Additional information

Weight 1.0 lbs

20 lbs, 40 lbs


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