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Problem with green foam in new wildlife pond

Hi all - I completed my new wildlife pond 2 or 3 weeks ago (not sure what day/month/year it is at the moment!!). After a couple of days the water was really clear and I could see to the bottom. Then after about 5 days my oxygenators arrived (I calculated the bunches I would need with an online calculator) and half I planted in the shelf about 20cm down and the rest I plopped in with the weighted things still attached to them, so they sank.

A few days or maybe 1 week after this the pond has started to accumulate a lot of what can only be described as green foam. It is hundreds and hundreds of air bubbles and a bright green colour. The water colour itself is also a murky dark green. Does anyone have any idea what could be causing this?

I noticed that many of the oxygenators that I plopped in have floated back to the surface and most look half brown/half green (including those actually planted in the shelf). Is it a problem with these plants that is causing it? Have I done something (another thing!) wrong?


  • KeenOnGreenKeenOnGreen Posts: 1,630
    Could you take a photo for us?  It will help to advise you.

    We just divided a lot of our oxygenators at our home pond, and moved them to our allotment pond.  They looked terrible for weeks, like yours, and are still a bit brown and half dead, but there is definite signs of growth, and we know that in a few weeks they will be romping away.  In my experience, even if they float to the surface, they usually still survive.  Be patient with them, and as long as they get enough sun, they will probably recover.

    The main problems we get with our pond are duckweed (like thousands of tiny little green leaves which carpet the surface) and pondweed (which is a bit like green Candy floss, and which floats under the water and all around the plant pots/roots/stems).

    Your problem could be pondweed, but it might also be an excess of algae, due to it being a new pond.  This is very common with new ponds, where there is an inbalance from too much nutrients.  You can buy barley-based products to put in the pond and which will get rid of the algae, without harming anything.

  • Pete.8Pete.8 Billericay, EssexPosts: 8,555
    Yes, I'd very much agree with it being a new pond and the time of year.
    Algae are very basic plants and they are among the first to be able to start growing, so for a while, you get algae. The pale green foam is a combination of algae and bubbles. I leave it for a while as it's home to all sorts of bugs and a haven for new tadpoles. It starts to break up in a few weeks as your plants will get going and starve the algae of food. It can then be netted out quite easily.
    The green water is also algae and will clear in time for the same reasons.
    Blagdon Barley Straw Extract combined with their Sludgebaster will help keep algae under control - or it does in my pond :)
    Knowledge is knowing that a tomato is a fruit.
    Wisdom is not putting it in a fruit salad.
  • FairygirlFairygirl west central ScotlandPosts: 46,369
    Yes - don't worry too much @gilla.walmsley
    What types of oxygenators did you get? Some can be a bit more foamy than others  ;)
    Some are also floaters rather than sinkers, if you get my drift....
    I use watercress quite often as it also uses up the nutrients in the water. Our pond hasn't warmed up enough yet though, so still quite clear.
    I bought some other stuff recently though, as I was getting another piece of liner for a little project. Can't remember what it is though. Hopeless, me  :(
    It's a place where beautiful isn't enough of a word....

  • These are the only two pics I took a few days ago before I cleared it all out with a pond net today. (Ignore the general state of it, it's very much not finished externally!) What's hard to make out in these pics is that everything you can see is just tiny clusters of air bubbles, which have turned bright green . But having had a quick Google after reading your messages perhaps this is what algae looks like? I also just Googled pond weed and duck weed and they are what I thought algae was! So perhaps I'm worrying over nothing?

    Ah - I fished a load of the browning floating oxygenators up and out of the pond too - oh dear! 

    My oxygenators are: 
    Water violet
    Water crowfoot

    And I also have some Willow Moss on order

  • Pete.8Pete.8 Billericay, EssexPosts: 8,555
    It's a new pond and will take time to mature.
    The algae will clear and the best way is to get lots of plants in and around your pond and let nature do the rest for you.
    Puddle Plants is a good online source for wildlife ponds.
    Brooklime grows like crazy in my pond and once hornwort gets established it's very well behaved. Water mint is good too and there is a huge choice of plants available to transform your pond. Give it a year and it'll be looking amazing
    Knowledge is knowing that a tomato is a fruit.
    Wisdom is not putting it in a fruit salad.
  • FairygirlFairygirl west central ScotlandPosts: 46,369
    I wouldn't worry too much. You don't have anything else around the pond yet,and gradually it will all settle. The oxygenators will multiply too. I expect it's the water violet you've pulled out - it does look manky and dead quite often!

    Once you have some different plants for various positions in the pond, and surrounding planting in place, it will rapidly improve  :)
    It's a place where beautiful isn't enough of a word....

  • GemmaJFGemmaJF Posts: 2,286
    It's algal bloom. Normal in a new pond and not related to the plants. The plants may suffer from the lack of light though, so if you could keep them in a bucket until it clears. Barley straw or extracts work very well to clear it, but nature will sort it out in the end.
  • Fishy65Fishy65 Posts: 2,270
    Yep as others have said, an algae bloom which is entirely natural in a new pond. Your pond being young, it needs time and the introduction of the higher water plants to begin gobbling up all those nutrients that the algae (that green froth) is doing right now. Once the higher plants become established, and probably a lot sooner, that froth will vanish and your water will clear as the algae dies off.
  • Thank you very much for the reassurance everyone! Great to know it's not something I'm doing wrong :smile::smile:
  • FairygirlFairygirl west central ScotlandPosts: 46,369
    edited May 2020
    @gilla.walmsley- I knew friends who moved into a new house and inherited a pond, albeit an ornamental one. Iit was just at that time when water was warming up, and the whole thing turned green. They made the mistake of emptying it out and refilling. When I was over a month or two later, I explained to them about the water warming up - they just didn't know and thought something was wrong with it.
    Of course, it had all settled down and was fine by the time I visited  :)
    It's a place where beautiful isn't enough of a word....

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