Duckweed in a pond is an interesting situation. Some pond owners (particularly those with smaller ponds) often love having it around, and sometimes add it to their pond and would never dream eradicating it.
By the way…I talked about duckweed in this pond tip just in case you might wonder what it looks like and how it differs from algae.
Large pond owners however usually have a different opinion of duckweed. For them, a little might be ok, but often, when conditions are right, duckweed can grow like crazy and cover the entire surface of a pond.
The plant actually isn’t all bad to have around. It’s a powerful user of any organic nutrients in the water so in a sense, it can help clean and balance the pond out. And it will go away when and if the weather cools enough in moderate climates.
Even with all this, many pond owners want to treat it, and in terms of chemicals, they’ll often resort to something with Fluridone in it. Some brand names of products with Fluridone include Sonar or WhiteCap. These treatments are quite expensive with small amounts, such as 8oz. costing several hundred dollars.
Fluridone is best used really early in the growth cycle when the plant is weaker and it will provide better control that way.
By the same token, we have had success in lowering nutrient loads in a pond with a beneficial bacteria treatment routine before the duckweed starts growing well, and in keeping nutrients low, it will have a more difficult time taking off. Wait too long though, and a bio won’t have much affect.
The problem with both of these treatments is that most pond owners end up waiting, or getting caught off guard when the plant expands quickly over their pond. And by then it may be too late.
Particularly when temperatures get really hot, as they have been this summer around most of the U.S., it’s not a good idea to treat duckweed chemically. As we’ve stressed time and time again, massive die off of a plant in a pond (usually due to a chemical treatment) will pull a lot of oxygen from the pond, and in doing so, will likely hurt any fish in the pond.
So what’s a pond owner to do about duckweed?
Well there is one option (actually several, but no other works as cheaply and effectively over a wide area), and it totally eliminates the need for any additive in the pond at all. It requires some manual labor, but that’s not a bad trade-off in a lot of cases. You can build this DIY removal tool for under $25 and with a little tweaking, you can usually get it to work pretty well.
Watch the video below to learn more…and please feel free to leave your comments and suggestions below.