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  1. #1

    duckweed removal recommendations

    Hi all

    friend is having difficulty removing duckweed from his large natural koi pond.
    looking for an effective chemical as he,s tried to physically remove it which has been very difficult due to various rocks plants etc surrounding the pond.

    thanks Ian



  2. #2
    Senior Member Rank = Kyusai Koiz's Avatar
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    How bizarre. I was just sorting through my 'koi shelf' this morning and found this that's never been opened. I have no idea why I even bought it as I've never had duck weed!

    If you are driving by the PE26 area anytime you are very welcome to have it!

    It doesn't appear to have a sell by date on it but it's gotta be 5 years old. Its got a lot number so you could always ask NTLabs on Monday duckweed removal recommendations

    Sent from my SM-N910F using Tapatalk
    11,440L Raised Pond, BD, Oase ProfiClear, Bitron 55W, 2x10k Aquaforte Varios, Skimmer to Waterblade

  3. #3
    Extreme Koi Member Rank = Yonsai LouiseR's Avatar
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    Duckweed is an absolute menace when it finds its way into a pond.

    Chemicals are available that will nuke duckweed (aquatic herbicides), but they are invariably toxic to fish and other plant life so are not an option. Even were your friend to remove the fish to treat chemically, he/she would then be left with the problem of safely disposing of the water, and then successfully removing the chemical residue from the pond walls and filtration system - not something anyone would recommend!

    There are non-chemical products that can be used, such as the one Koiz posted. Blagdon make a similar product, as do Eco Pond. They claim to work by reducing nutrients that duckweed thrives on, usually by the operation of some sort of bacteria (it’s unclear why these products target duckweed but are otherwise plant safe). I think it’s doubtful that any of these products will actually eradicate duckweed not least since the two major plant nutrients, phosphate and nitrate, are both, at some level, continuously reintroduced to pond water i.e. tap water often contains phosphate and nitrate which will be reintroduced with regular water changes; fish food contains phosphorus which is converted to phosphate in fish waste; nitrate is a by-product of the nitrogen cycle, etc.

    Before going to the expense of adding any of these non-chemical products which are unlikely to provide a permanent solution, I think your friend would be better off trying the following:

    # Remove as much duckweed as possible manually on a regular basis.

    # Remove as much debris from the bottom of the pond, if any, as possible, and keep it clean. If there is a lot of muck on the bottom of the pond it would be better to remove the fish whilst doing this to avoid stirring up any hydrogen sulphide gas trapped in the debris.

    #. Carry out regular water changes (using a suitable dechlorinator).

    # Add one or more (depending on pond size) surface skimmers to the pond.

    # Increase water movement and aeration to the pond - please see this article: https://lochnesswatergardens.com/blo...d-in-your-pond

    These steps, particularly increasing aeration, should significantly knock back the duckweed, and might in the long term be sufficient to eradicate the menace.

  4. Thanks Koiz, shumboom Thanked / Liked this Post
 

 

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