Pond duckweed removal problems

by Humphry @ 5:44 pm May 25, 2009 -- Filed under: garden design, ponds and water features   

duckweed_pond_removalWhen I first saw duckweed, I loved it. Thinking I had found a perfect lawn I leapt in the air and landed in the water, too shocked to scream.

So there are three ways of getting rid of duckweed, two bad and one good. The worst way is herbicides. We don’t want nasty chemicals in our gardens and we don’t want to waste money on chemicals. The next way is mechanical removal. It easy and you really feel you are doing something. But the duckweed grows back in a few days. The best way is biological control. If you have a biologically balanced pond you will not have a duckweed problem. And to balance you pond you must stop fertilizers from leaking into the water. Then you make sure you have oxygenating plants and some nice fish.

Download garden pond duckweed photograph

6 Comments »

  1. Duck weeed is a pain to many people but as far as I am aware does not cause fish problems you just can not see them !There must be something out there that deals with this problem. I am surprised that you have not said how you can get over this problem, because I am sure people like me would buy it.Besides that there are other oxygenating plants that do a good job by day but reverse the process at night,so you must get the whole process or why am I going to bother going to your site when there are numerous other sites that I have to look at for the same subject.SO now I will inform you of “with resprct” what I was hopeing to find.
    1 I would like to know about natural large ponds.
    2 The plants that grow in them.
    3 How to control them.
    4 A site that did not just have a bit of what happens but a site that you can look at and say I recognised that problem and sell me the cure.

    Comment by Dave Austin — June 5, 2009 @ 3:04 pm

  2. Sorry Dave, but you can’t ‘buy’ a good ‘cure’ for duck weed, any more than you buy a good cure for obesity or flabby muscles. You have to work at the problems and, for ponds, the aim is ECOLOGICAL BALANCE between flora, fauna, nutrients, light, oxygen etc. A fat belly is a symptom of other problems and so is duck weed. I will plan to do another post on how to achieve ecological balance, but we won’t be able to sell you a magic cure!

    Comment by Humphry — June 7, 2009 @ 3:25 pm

  3. We have a large pond which is 4ft deep in places and have many plants including lilies, reeds, canadian pond weed and recently introduced, watercress. The watercress has got rid of the blanket weed but we still have this terrible duckweed problem. We dont want to use chemicals – Thompson & Morgan have just emailed me an advert for biologically friendly stuff which you put in the water to get rid of the duckweed. Its called Pond Wizard. Question is, should we buy it? We have a huge pump and a filter system the size of a coffin, loads of fishes which are healthy together with shrimps and such like so I would say the pond is well balanced ecologically.

    Comment by Liz McPherson — August 4, 2009 @ 5:52 pm

  4. There are many well balanced natural waterways that are infected because this is an aggressive weed, lets not under-estimate how pervasive it is and start blaming the person suffering – the analogy with flabby muscles is poor because duck weed is more like an infectious disease which the victim can’t avoid rather than some poor ‘pool lifestyle choice’.

    I am struggling with the same issue despite a very healthy pond – mechanical removal is effective but a weekly task. I aim to reduce my water level to drain a shallow area over the winter – this will leave a well defined area which I can remove all surface weed and clean the sediment on the bottom more easily. The frosts should deal with drained shallow area and hopefully my efforts combined with water changes, will provide a long term fix to the problem that started with an infected plant I bought at a local shop.

    Comment by Mark DRUMMOND — October 9, 2009 @ 5:19 pm

  5. I am having a torrid time controlling the duck weed in my pond. I am actually a retailer of blanket weed control products, so am on top of things with regards to this (obviously!). However, for duck weed I can find no solution. I haven’t actually heard of the Pond Wizard, but I think I will check it out. Has anyone heard any feedback on this product?

    Comment by James - Blanket Weed Control — November 11, 2009 @ 12:12 pm

  6. I must be the only person that actually likes duckweed then. It’s good cover for fish in the early part of the year before other plants have woken up. Fish like eating it and it also helps to remove excess nitrates from your pond. Hence if you have too many nitrates you’re likely to have a duckweed ‘problem’.

    Apart from all that it looks nice – providing the whole pond isn’t covered. It’s easy to remove just use the hose to spray it to one side and scoop it out. Duckweed also makes good compost and is a delicacy in some parts of the world.

    Comment by Helen — March 29, 2010 @ 12:10 am

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