Can you use roundup in a pond? (Important guide)

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Nobody wants to see their pond encroached upon by weeds. Keeping it protected is important, which raises the question: can roundup be used in a pond?

Roundup should not be used in a pond as it contains the Surfactant polyethoxylated tallow amine, which is illegal in aquatic environments. By using Roundup in a pond, you are exposing fish and other aquatic invertebrates to this toxic chemical, which ultimately accumulates in the tissues of these animals, causing serious health issues and even death.

What would Roundup do to your pond if you used it anyway? Are there any other reasonable, effective alternatives?

What Roundup Does to Your Pond

Like most herbicides, Roundup contains glyphosate which kills weeds. This product was designed strictly to kill weeds in a soil-based environment and was never intended to treat weeds in an aquatic environment.

Rather than simply killing off the weeds as it would in a soil-based environment, when exposed to a pond the glyphosate latches onto the soil and other organic particles, quickly contaminating the aquatic environment.

This foreign chemical immediately impacts marine life in the pond by inducing oxidative stress in the fish aqua life residing there. To make matters worse, glyphosate is durable in aquatic environments and can take up to one hundred and forty days for the microbes to break it down. The negative effects of Roundup on the pond ecosystem cannot be understated.

How to Protect my Pond From Weeds?

Fortunately, there are safe alternatives to get rid of weeds without compromising the health of the pond. There are several safe and effective ways to do this. These include manual removal, natural barriers, aquatic-based herbicides, boiling water, and even salt.

Manual Removal

Strictly accounting for the marine life in the pond, this is the most ideal option, and it poses no legitimate risk or harm toward them, as opposed to the other options. This works best when the weeds are still scarce and smaller in size. If the current weed situation in the pond falls into this category, simply grab a pair of gloves and pull the weeds out from the pond.

If the weeds have grown and are more mature, it will be easier to simply use a rake. When using a rake, carefully entangle the teeth of the rake into the weeds, making sure to check that all other healthy plant life is out of the way, then pull up, lifting the weed roots out from the soil.

Natural Barriers

Another simple but effective way to protect your pond against weeds is by using natural barriers. Simply purchase any type of outdoor weed barrier fabric, and place it on the ground of the pond.

To ensure that the fabric stays down and is not pushed around by weeds, place heavy items such as rocks across the edges of it. This barrier will slowly but effectively kill off all the weeds in your pond by starving them of sunlight and nutrition.

Aquatic Based Herbicides

Unlike Roundup, which was created for soil-based weeds, there are herbicides created specifically to treat aquatic plants such as Aquashade, Bluesprings, and Crystal Blue. These herbicides can effectively kill off the weeds found in ponds, and unlike traditional herbicides, are designed specifically to break down quickly in order to preserve the health of the pond.

Before purchasing, make sure to read the label to know exactly what chemicals you will be introducing into your pond. It is also important to note that the time these herbicides are applied to the pond has a significant effect on how effectively it will hinder weed growth. If these herbicides are used in the winter, although it may kill the weeds, the effect on future weed growth is limited.

In contrast, if these same herbicides are applied in the spring when weed growth is more rampant, it can more effectively kill new and young weeds, while still maintaining a safe environment for the fish that reside in the pond.

Herbicides should also be avoided during the summer when the vegetation has become thicker, there is a greater risk on the fish due to a higher dependence on the oxygen provided by the weeds. It is crucial not just to know what herbicides to use, but also when to use them.

Boiling Water

This solution generally takes a couple of days to kill the weeds off but is among the most convenient options available. Simply heat up the water to at least boiling point (212 F) and put it into an appropriate sized container, depending on how many weeds are in your pond.

Proceed to douse all the weeds around your pond with this hot water, which will kill the root and plant tissue, causing the weed to eventually wither and die off. It generally takes about two days from the time the boiling water is applied to the time where the weed shrivels and dies.


Another simple and effective way to kill off pond weeds is by using salt, which will starve the water out of the weeds. Mix salt with water at a two to one ratio, which will be sufficient to kill the weeds. Then use a funnel and slowly walk around the pond, making sure to douse the weeds with the saltwater.

Dredge Your Pond

If the weeds have become common enough in your pond that it is becoming hard to manage, dredging is one of the best options available. Dredging will remove the smaller and harder to reach weeds that reside at the bottom of the pond, in addition to eliminating any potential weed growth that may be occurring in the soil. Although dredging can be a long and arduous process, the results are well worth the hassle.

Dredging creates allows more nutrient-poor soil to be revealed, creating a much more difficult environment for weeds to grow in. Additionally, it limits the weeds’ exposure to sunlight, while making it more difficult for new weeds to take root. This process can be longer and more expensive, but the effectiveness of it makes it an attractive option, especially if the weeds are out of control.

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We always wanted a fountain of some kind at our house, but professional installation was just too pricey. So, we decided to make our own little fountain and after learning how, we thought we should share our experiences to help people in our same situation.

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