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Mouldy pebbles for new pond

frog39frog39 Posts: 4
in Wildlife gardening
Hi I have recently made a wildlife pond and I've been given some beach pebbles from a friends garden.  The pebbles have got black mould on them.  Does anyone have an idea of how to clean them safely before adding them to my pond edges and beach area?  Any tips would be appreciated thanks!

Posts

  • JennyJJennyJ Posts: 10,120
    A bucket of water and a scrubbing brush would work if there aren't too many. Or maybe a good blast with a hose or pressure washer.
    Doncaster, South Yorkshire. Soil type: sandy, well-drained
  • BobTheGardenerBobTheGardener Posts: 11,391
    Any chance of photos?  A mould is unlikely but there are some black lichens which may have made a home on them, especially if the black marks are roughly circular, like here:

    A trowel in the hand is worth a thousand lost under a bush.
  • frog39frog39 Posts: 4
    JennyJ said:
    A bucket of water and a scrubbing brush would work if there aren't too many. Or maybe a good blast with a hose or pressure washer.

    Thanks JennyJ i've tried but it's not shifting it unfortunately - sorry I should have said that in my post :)

  • Pete.8Pete.8 Posts: 11,142
    As Bob says a photo would help.
    I have some cobbles around one of my ponds and sometimes wildlife knocks them into the pond.
    If I a year later I remove the cobble, the bottom of the cobble that has been laying in the silt for 12 months is stained black, but after a few months out of the water the stain fades.

    Billericay - Essex

    Knowledge is knowing that a tomato is a fruit.
    Wisdom is not putting it in a fruit salad.
  • JennyJJennyJ Posts: 10,120
    If a good scrubbing doesn't shift it then it's unlikely to come off in the pond and cause harm.
    Doncaster, South Yorkshire. Soil type: sandy, well-drained
  • frog39frog39 Posts: 4
    BobTheGardener said:
    Any chance of photos?  A mould is unlikely but there are some black lichens which may have made a home on them, especially if the black marks are roughly circular, like here:


    Thanks Bob - yes that is exactly what is on them!  Sorry I'm not the greatest with technology so can't promise a photo! 

  • LynLyn Posts: 23,085
    Just use them as they are, lichen won’t hurt anything.
    When we renovate headstones or war memorials we use chemical cleaners to soak it, then use a wire brush.
    You don’t want to do that in your pond.
    Gardening on the wild, windy west side of Dartmoor. 

  • BobTheGardenerBobTheGardener Posts: 11,391
    edited May 2020
    I agree with @Lyn and would just use them as-is.  You don't want even the merest trace of chemicals anywhere near your pond as aquatic life is extremely sensitive.
    A trowel in the hand is worth a thousand lost under a bush.
  • mrtjformanmrtjforman Posts: 331
    edited May 2020
    Well the article you posted bob mentions the only real remedy is bleach. Bleach is toxic to aquatic life sure but it also breaks down within a few months even faster in sun. 
    I have used bleach to clean aquatic ornaments -rinsed them off well and soaked and if any amount did seep out it would be minimal and then degrades. Haven't had a problem - can't see it being too much of an issue in a pond but I don't want to be held responsible for bad advice so yes bleach is toxic and use at own risk.
    Also, I should mention the stones would get covered in Algae in a pond anyway! You won't be able to avoid this and the marks would most certainly be covered by next year with dirt and algae anyway.
  • frog39frog39 Posts: 4
    Thanks everyone - I'll go ahead and use them as they are :)
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