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United Phosphorus Inc Hydrothol 191 6020396 Herbicide 20lb.

4.0 4.0 out of 5 stars 350 ratings
Amazon's Choice highlights highly rated, well-priced products available to ship immediately.
Amazon's Choice in Water Garden & Pond Treatment by United Phosphorus Inc
$117.00 $0.37 per Ounce
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Purchase options and add-ons

Brand United Phosphorus Inc
Item Weight 20 Pounds
Item Form Granules
Active Ingredients Herbicide
Coverage 1000 square feet

About this item

  • Is a concentrated aquatic herbicide/algaecide effective against a wide variety of submersed aquatic weeds and algae.
  • Please refer to product label for dosage rates and use instructions.
  • 20 lb
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Product details

  • Is Discontinued By Manufacturer ‏ : ‎ No
  • Package Dimensions ‏ : ‎ 19 x 14.5 x 6 inches; 20 Pounds
  • Date First Available ‏ : ‎ December 12, 2014
  • Manufacturer ‏ : ‎ United Phosphorus, Inc.
  • ASIN ‏ : ‎ B00QXNR7AE
  • Customer Reviews:
    4.0 4.0 out of 5 stars 350 ratings

Product Description

This concentrated aquatic herbicide-algaecide is effective against a wide variety of submersed aquatic weeds and algae. Application rates range from 3 up to 270 lbs per acre foot of water. Normal granular application rates for spot treatment of submersed weeds is 12 lbs per 1,000 sq ft with 4 ft avg depth. Hydrothol treated water may be used for swimming, fishing, livestock watering and irrigating turf, ornamental plants, and crops with few exceptions (please refer to the label).

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Customer reviews

4 out of 5 stars
4 out of 5
350 global ratings

Customers say

Customers are disappointed with the value of the weed moss control agent. They say it's very expensive for it not to work. Customers also disagree on performance and quality.

AI-generated from the text of customer reviews

4 customers mention4 positive0 negative

Customers find the weed moss control agent simple to use. They mention the directions are easy to read, and the product is easy to broadcast by hand or with a hand broadcaster. Customers also say the ordering process was quick and easy.

"...It is in pellet form and easy to broadcast by hand or with a hand broadcaster. So I distributed the pellets by hand as it was along my sea wall...." Read more

"Simple to use" Read more

"Worked great! All the weeds are gone where we used this. Easy to use." Read more

"Easy to use! However it has not killed a single thing in the pond!" Read more

33 customers mention12 positive21 negative

Customers are mixed about the performance of the weed moss control agent. Some mention that it works great, while others say that it didn't work as advertised, with very little results. Some say that the product didn''t seem to work on all types of weeds, and that the mosses flourished after two applications.

"Had thick, at edge, stringy weed growth from sub surface. Took a 2/3 weeks to see results. It did work! Weeds cleared.But two things 1...." Read more

"This product is fabulous. The seaweed that was at my shoreline is almost gone after one week of application...." Read more

"...It doesn't do anything. Save your money." Read more

"...product for the weeds in the lake behind my house and the results have been disappointing." Read more

9 customers mention5 positive4 negative

Customers are mixed about the quality of the weed moss control agent. Some mention it slowly does the job, while others say it didn't kill their pond weeds.

"...Killed the grass and also the algae." Read more

"...I spread it in the water as instructed, but it didn't kill any weeds. Now I'm using another product which works better...." Read more

"slowly does the job, kills my pond weed." Read more

"Kills aquatic plants" Read more

6 customers mention0 positive6 negative

Customers are dissatisfied with the value of the weed moss control agent. They mention that it is very expensive and like flushing money down the toilet.

"...Ordering was quick and easy. It was pricey but if it worked then it's worth it. It was delivered earlier than anticipated and was packaged well...." Read more

"...I found this frustrating and expensive." Read more

"very expensive product but works as claimed" Read more

"...Pricey and literally did nothing at all. Skip it." Read more

Well 8 days after treatment and weeds still there
1 Star
Well 8 days after treatment and weeds still there
So ordered this to help me clear out my lake sea wall of several different lake weeds both underwater and sticking out of the water. Ordering was quick and easy. It was pricey but if it worked then it's worth it. It was delivered earlier than anticipated and was packaged well. Directions were easy to read and I also read several reviews of what helped other buyers. Basically, I was looking at a 7 to 10 day window to see difference. It is in pellet form and easy to broadcast by hand or with a hand broadcaster. So I distributed the pellets by hand as it was along my sea wall. I video taped it to try to see difference. Its 8 days later and my lake weeds are still very nice and green with no changes. Because we had a cool front move through the area on the 4th and 5th day with rain, I figure I will give it a few more days to see a difference but so far, I have wasted 130.00. My neighbors are watching the progress with me daily because they have the same issue that I have. We will be trying something diffent because so far, this product is a bust! It doesn't do anything. Save your money.
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Top reviews from the United States

Lisa
5.0 out of 5 stars Very effective on seaweed
Reviewed in the United States on August 2, 2021
Verified Purchase
This product is fabulous. The seaweed that was at my shoreline is almost gone after one week of application. I thought I would have to pull out by hand the treated seaweed upon it turning brown. We have a bit of a current in my channel that is just washed away. I thought the pricing is quite reasonable, my neighbors have spent far more than I on their products to rid the seaweed.
4 people found this helpful
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whichatich
5.0 out of 5 stars Seems to work pretty good. My approach has been to treat small ...
Reviewed in the United States on June 7, 2017
Verified Purchase
Seems to work pretty good. My approach has been to treat small areas at a time and I definitely see a reduction in the hydrilla. I have no other aquatic herbicide to compare it to but the areas I have not treated yet are thriving and the area I have it's greatly reduced. I'm also treating in the beginning of summer which is the worst time when the weeds are in growing the most. Our lake sees a lot of traffic so given the circumstances I can't expect much more really.
7 people found this helpful
Helpful
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Nobody
4.0 out of 5 stars Granular application for pond weeds
Reviewed in the United States on July 9, 2021
Verified Purchase
Had thick, at edge, stringy weed growth from sub surface. Took a 2/3 weeks to see results. It did work! Weeds cleared.
But two things 1. Aprx two onths after application. Weed growth has started again.
2. A established willow tree, near pond overflow, showed signs of exposure. Leafs on tree have turned brown. Not sure if it will survive.
4 people found this helpful
Helpful
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Kezbeth
1.0 out of 5 stars Well 8 days after treatment and weeds still there
Reviewed in the United States on October 31, 2021
Verified Purchase
So ordered this to help me clear out my lake sea wall of several different lake weeds both underwater and sticking out of the water. Ordering was quick and easy. It was pricey but if it worked then it's worth it. It was delivered earlier than anticipated and was packaged well. Directions were easy to read and I also read several reviews of what helped other buyers. Basically, I was looking at a 7 to 10 day window to see difference. It is in pellet form and easy to broadcast by hand or with a hand broadcaster. So I distributed the pellets by hand as it was along my sea wall. I video taped it to try to see difference. Its 8 days later and my lake weeds are still very nice and green with no changes. Because we had a cool front move through the area on the 4th and 5th day with rain, I figure I will give it a few more days to see a difference but so far, I have wasted 130.00. My neighbors are watching the progress with me daily because they have the same issue that I have. We will be trying something diffent because so far, this product is a bust! It doesn't do anything. Save your money.
Customer image
Kezbeth
1.0 out of 5 stars Well 8 days after treatment and weeds still there
Reviewed in the United States on October 31, 2021
So ordered this to help me clear out my lake sea wall of several different lake weeds both underwater and sticking out of the water. Ordering was quick and easy. It was pricey but if it worked then it's worth it. It was delivered earlier than anticipated and was packaged well. Directions were easy to read and I also read several reviews of what helped other buyers. Basically, I was looking at a 7 to 10 day window to see difference. It is in pellet form and easy to broadcast by hand or with a hand broadcaster. So I distributed the pellets by hand as it was along my sea wall. I video taped it to try to see difference. Its 8 days later and my lake weeds are still very nice and green with no changes. Because we had a cool front move through the area on the 4th and 5th day with rain, I figure I will give it a few more days to see a difference but so far, I have wasted 130.00. My neighbors are watching the progress with me daily because they have the same issue that I have. We will be trying something diffent because so far, this product is a bust! It doesn't do anything. Save your money.
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Customer image
Customer image
6 people found this helpful
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Deb
5.0 out of 5 stars Great product for getting rid of "Pond Weed"
Reviewed in the United States on January 14, 2021
Verified Purchase
I spend years trying to eliminate "Pond Weed" from my pond - spending a lot of time using other products to control or rid the pond weed. This product was great - in a week I could see a difference - cleaned the pond and no longer have a mat of weed from the bottom to the top of the pond.
4 people found this helpful
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King
3.0 out of 5 stars not as effective as expected
Reviewed in the United States on April 30, 2023
Verified Purchase
I am using this product for the weeds in the lake behind my house and the results have been disappointing.
2 people found this helpful
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Theodore Ketron
5.0 out of 5 stars This stuff is amazing, finally figured out what to buy to take ...
Reviewed in the United States on May 17, 2018
Verified Purchase
This stuff is amazing, finally figured out what to buy to take care of leafy pond grass I've been trying to get rid of for years. Killed the grass and also the algae.
12 people found this helpful
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Jim Moris
5.0 out of 5 stars As advertired
Reviewed in the United States on July 16, 2022
Verified Purchase
The product was just as advertised. No surprises. Fast shipping too.
One person found this helpful
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