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New pond surface has a film

JohnB47 Posts: 2,566 Forumite
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edited 21 August 2023 at 11:59AM in Gardening
OK, reclaimed pond, all old stuff removed, new liner filled with rainwater, now around 7 weeks old.

New plants added over time and all's well, apart from a cloudy bloom of frothy green stuff that appeared after about a fortnight and which I've been able to keep down using a bottle brush thingy to twist in the water and scoop it up like making a candy floss. That seems to be reducing now, all on it's own.

About a week ago I noticed, from the kitchen window, that the pond looked sort of milky. As I went towards the pond, I saw that it was a thin surface coating giving that effect. It isn't oil - there's no rainbow effect you get with an oil film on water. It just looks like a fine layer of dust, or maybe pollen. There's the odd little 'break' in the surface coating too.

After first noticing it, it rained a fair bit and the film disappeared. But about two days later it came back.

I've read up about this and one suggestion is 'biofilm' but that seems to be described as thicker than what's on my pond.

Maybe it is just dust or pollen. The plants look to be doing OK.

Any thoughts?


  • jlfrs01
    jlfrs01 Posts: 285 Forumite
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    Basically, there's too much decaying matter in the pond - you need more "good" Bacteria to break it down and the obvious thing to do is to install a filter if you have electricity within reach. You could "dredge" the pond with a net to catch anything which may be at the bottom such as leaves for example, that would help as well.
  • JohnB47
    JohnB47 Posts: 2,566 Forumite
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    Thanks. Actually there is very little decaying matter there. It's too young a pond. There are a few leaves but they aren't starting to decay much. We have added oxygenators - they sit at the bottom and some of the plants we have in their are also supposed to add oxygen.

    In general the pond water is pretty clear - we can see right to the bottom.

    Perhaps the pond is going through stages before it reaches a balance?
  • twopenny
    twopenny Posts: 5,896 Forumite
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    Have you got any of the oxygenating weed in there to help clear the water?
    I've just got a solar water fountain for £20+ to go in mine in the hope it helps clear the water.
    Your's may just be the natural film often on still water. You only see it in certain lights but I'd say it was dust laying on the surface ie surface tension it's too light to sink.

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  • Keep_pedalling
    Keep_pedalling Posts: 17,169 Forumite
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    It’s almost certainly from decaying algae, you won’t have got it all out with the bottle brush. Nothing to worry about it will go eventually.
  • Richard1212
    As Keep_pedaling says, it sounds like decaying algae ( unless---unlikely--- caused by sap or oily substance falling from an overhanging tree). If you haven't got a pump and filter, I highly recommend you buy one, and have a fountain. Lots of oxygenating plants too. Fish should love all that !

    Give it a few months after the above and , if problem is still the same, then you either didn't clean out the old pool properly, leaving a fungus or a bad algal infection. Good luck----what is a garden without a pretty fish pond and fountain ?
  • JohnB47
    JohnB47 Posts: 2,566 Forumite
    First Anniversary Name Dropper First Post
    Thanks everyone. It looks worse tonight - definitely a greenish tinge to it now. We do have oxygenators in there but perhaps we need better ones!

    BTW, it's a brand new liner, rain water, all new plants, no fish!

    I'm not too worried. Hopefully it will settle after a few months.
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