Rampant weed/algae - advice needed

[vole-woman]

I've had a lovely garden pond for 2 /12 years now and managed to keep the duckweed, Canadian pondweed and blanketweed in check by regularly pulling the stuff out.

But recently we've had a new slimy weed, sort of algal filaments, which is really hard to scoop up as it slithers away (not like blanketweed which all comes up in a big felty mass). It coils under the surface, but it's in the body of the pond too. It grows REALLY fast and looks as though it could choke up the water within a few weeks if left alone. The temperature/weather doesn't seem to make any difference.

I've tried adding an anti blanketweed chemical to the water, but that's not had any obvious effect.

Has anyone got an idea of how I can proceed?

[Dogghound]

Can you lower the ponds water level or is it on the ponds base too? I suspect this growth has been caused by higher nutrient imput into the pond, has anything like grass cuttings, fish, leaves, chemicals etc been getting into the pond?

[vole-woman]

"has anything like grass cuttings, fish, leaves, chemicals etc been getting into the pond?"

Not that I'm aware of (though there was a dead woodmouse floating on the surface yesterday morning!)

I think the filaments go right through the body of the water and aren't just confined to the surface.

[fox403]

ok with algae few ways to get rid of it first is a uv light if its free floating and can pass thought a pond pump to a uv this will kill it ...next chemical ,,,now hundreds on the market I work in an aquatic outlet and by far the best is oase string algae remover £18 do 10,000 lts natural product so not harm anything else in pond, best advice is get a balance in pond, its sunlight and nutrients that cause all algae’s so by putting cover on top pond as in lily’s ect or fast growing oxygenating plants it will make algae compete with it for food

[vole-woman]

That's so helpful, thanks! So oase string algae remover? I'll see if I can find it.

[vole-woman]

I've just bought some oase string algae remover, got it home and see on the box it says "not suitable for wildlife ponds". In your experience, fox, is it safe to use or will it harm my water life?

[Red Robin]

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How big is your pond, vole-woman? Surely the best way is to remove enough algae (not all) by hand and help the natural balance by the use of lilies cover, shade, and water snails which like to graze it.

Any commercial additive is a last resort and should be avoided even if considered to be harmless.

[Gill Catton]

Its definately a nutriant problem. Microscopic algae is an important part of a pond's ecosystem providing food for slightly less microscopic animals which then feed other animals and personally I'd be reluctant to put anything in that kiils algae for this reason.

So you could maybe think of where the nutriants are coming from. Do you feed anything in the pond? Do you fertilise the lawn and could water from a fertilized lawn make it into the pond? Have you added any new plants in pots with soil in? Do you get ducks? Does the dog wash (and maybe wee) in it?

Its a bit of a rubbish growing time now but you can try adding something like horn wort which will grow really quickly in nutriant rich water and is very easy to hoik out the reducing the available nutriants for algae.

[vole-woman]

The pond is an 8 shape, with the top half about 1/12 metres in diameter and the bottom 2 1/2 metres diameter. It goes from about 3/4 to 1 m deep.

I've gone over and over what might have changed re the balance and can't come up with anything. The garden's been pretty much left alone this summer and autumn because my husband's been in hospital, and the only maintenance has been my father in law mowing the grass. Haven't seen any ducks on the water or anything else unusual, apart from a cat from time to time (just installed a cat scarer today).

The only thing I can think of is that maybe one of my sons has been pond dipping in the fields and brought some alien algae home on his net. Might this be the cause?

I've tried scoooping it out by hand/with a net, but it's not like ordinary 'felty' blanketweed that comes up in a blig clump. It's more slimy than that, almost like mucus, and very hard to get out. It slithers through your fingers.

Shoukd I try horn wort, then?

[Gill Catton]

Originally Posted by vole-woman

The pond is an 8 shape, with the top half about 1/12 metres in diameter and the bottom 2 1/2 metres diameter. It goes from about 3/4 to 1 m deep.

I've gone over and over what might have changed re the balance and can't come up with anything. The garden's been pretty much left alone this summer and autumn because my husband's been in hospital, and the only maintenance has been my father in law mowing the grass. Haven't seen any ducks on the water or anything else unusual, apart from a cat from time to time (just installed a cat scarer today).

The only thing I can think of is that maybe one of my sons has been pond dipping in the fields and brought some alien algae home on his net. Might this be the cause?

I've tried scoooping it out by hand/with a net, but it's not like ordinary 'felty' blanketweed that comes up in a blig clump. It's more slimy than that, almost like mucus, and very hard to get out. It slithers through your fingers.

Shoukd I try horn wort, then?

Very odd... I know the stuff you mean though, I used to get it in my fish tank too! It can't hurt to try hornwort though it may well vanish all by itself as it gets really cold.