Green Pond

Even through the last couple of months of January and February, the pond is green and I can't see what it going on.  There are a couple of dozen frogs in there spawning at the moment.  I have tried taking a lot of the lily pad out last year and using a silt product, but it is still so bad.  I don't know how to get it back.  I would really like to be able to see into the pond at the wildlife - if there is any - apart from the frogs!


  • Hello Oz,

    For an interesting take on algae in ponds, read Richard's blog. Remove what you can by fishing it out. Leave it by the pondside for a while so that pond creatures can crawl back into the pond. If you have a large pond, the traditional method of dealing with algae is to put barley straw in there in spring, taking it out in the autumn. However for small ponds, you can buy liquid barley straw extract from garden centres, which does the same thing. It's good to remove dying lily pads, but living ones can help promote the shady conditions that you need. If your pond is in the sun, try planting shade-giving plants around it. Good luck!

    Emma team

  • Hi Oz,

    After you have fished out what you can (if you can), you could try a solar pump/fountain.  Last year I bought a floating solar fountain and found that for the first time I had a clear(ish) pond with very little blanket weed.  Because I didn't have it running over winter, the pond became murky again but after running the fountain for a few days, it started to clear up.  I tried the barley straw extract last year and it didn't work for me but it might work for you.  I agree with Emma though, shading the pond either with floating plants or marginals is the way to go.  Algae just loves sunlight!


  • beachleybeachley Posts: 4

    For many years I used various chemicals but spent so much money to no avail......the only way i have found to prevent green algae is to use the straw bales.have just introduced the first one for spring.

  • geffgeff Posts: 4

    tried barley straw made no differance fitted uv sterilizer between the pump and filter box water crystal clear no blanket weed no algae Plus garden faces south west pond in full sun very little shade

  • JohannaWJohannaW Posts: 1

    Hello Oz and others,

    All the way from Holland this answer: see for advise . Most of the text is regrettably in Dutch, but maybe it can be translated. She is well known in Holland as a pond-specialist and is specialised on clear water-ponds without using any chemical, straw or filters. When your pond is already green her advise is "start again", remove all the water, plants and everything. Then start again with fresh tapwater (rainwater is far to acid), depending the hardness of your tapwater (in Holland the DH varies from > 12 tot < 4)) she ads "maerl" when DH < 12.

    Then - within 24 hours - you have to plant oxigen-plants: she advises especially Potamogeton Lucens, at least 4 bushes or 1 bucket/ m3 along with some other oxigenplants. Plus add a bucketfull of water from a healthy - clear - pond (we got it from Ada Hofman together with the oxigen plants we bought), she calls this a 'enting' (= grafting) which contains the necessary 'healthy' micro-organisms (which tapwater has not)

    Then wait and see ... Do not use filters-UV-light etc.

    In her botanic aquatic garden in the Netherlands, near the German border, with some 50 ponds (from very large to very small) she demonstrates that it worked. In my own garden (near Utrecht) we followed her advises and we have a clear water pond since 2009. She has written a couple of books about this, but I think it has not been translated in English.

    Joke (image= a dutch name, it comes from Johanna)

  • Hello

    Is it possible to put barley extract in a greenish pond when there are frog spawn in there.  We have one large clump and another smaller clump and both look like they have a green fuzz (algae?) on them.  We've been in the house/garden three years and this is the first year we have noticed this.

    Thanks, Claire

  • a tip to prepare your pond for next year is to plant as much shade giving plants now..gunnera mannicata (giant rhubarb) is fabulous for this and loves soggy sites plus light shade or sun suits it and it grows enormous if you have room for one...clear out any vegetation that has died back as it will enrich the water as it rots...try the above suggestions from everyone and hopefully with good maintenance and lovely new plants (always looking for an excuse to buy more) then your pond will flourish...

  • marshmellomarshmello Posts: 683

     Just joined - Hi all

    Your problem is you have too much suspended algae, making the water appear to be tinted green or even pea soup like, in appearance. You can’t see anything in your pond but algae. Not very appealing to the eye. Sunlight is the catalyst needed to culture the algae that you see. By limiting the amount of direct sunlight your pond receives, you are eliminating its source, thus reducing the algae bloom significantly.

    This is the real first step in getting your ponds algae bloom under control.

    Is your pond in direct sunlight ?!?!

    Is your balance of pond plants right ?!?! ....deep, oxgenators, marginal etc

    and NEVER fill the pond with tapwater unless its first been conditioned. This really does add to the problem. Rainwater is best.

  • i would add a UV steriliser as algae bloom are hard to control and uv sterilisers will combat the issue then when this has taken effect i would add more fast grwoing plants algae thrives on excess light and nutrient if there are either of these present then you will get algal blooms

    try added a shaded area to the pond and removeing and organic debris that could be decaying and adding nutrient

    the uv steriliser will work but if the underlying issue is not resolved the alge will return

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