Pond blanket weed

I cleaned out my pond early Spring by emptying it.  It's quite small, about 8ft at the longest and 6 ft at the widest with only part of it 3 ft  deep.  I put Blagdon Fresh Start I. To rebalance the water, put the plants back the few fish I had left and it seemed fine.  In May I restocked the fish and put net over it as I lost of lot of fish through herons over the years.  In the last few weeks I hve been plagued with blanket weed which I have to remove daily.  I use the Blagdons Barley Straw extract.  I have used this many times before and also the Barley Straw Floating packs.  However, I lost 5 fish on consecutive days and I'm not sure what's killing them.  Surely the Barley Straw extract is a natural product and has never killed fish Or is the blanket week damaging them. It is clogging up the pump on a daily basis and I am pulling it out by hand.  Any suggestions!??


  • hogweedhogweed Central ScotlandPosts: 2,706

    I find it strange that the blanket weed is clogging your pump. Is the pump in the deepest part of the pond? It may be that the pump intake is too close to the surface.  And do you have a UV filter attached to the pump. If you have, have you changed the bulb in it this year as it needs to be changed every year. If you do not have a UV filter it may be worth thinking about one. I have not had blanket weed since I put the uv filter in years ago.

    'Optimism is the faith that leads to achievement' - Helen Keller
  • Thanks hogweed.  No I haven't got a uv filter but will look into this.  

  • I have a koi pond with no plants in it but a vegetable filter which has plants in it and through which the water flows before returning to the pond.  This helps to keep the pond free of blanket weed as the plants take up the nitrates which feed the blanket weed.  A UV filter will not kill blanket weed as the blanket weed does not pass through it.  UV filters only get rid of green water which is algae suspended in the water, usually if you have blanket weed the pond water is quite clear.

  • NetfellaNetfella Posts: 54
    Sounds like there's an excess of nutrients in the pond. Either there is rotting vegetation in the bottom of the pond (although you said it was emptied earlier in the year), excess fish food/fish poo from over feeding or nutrients running into the pond from the surrounding earth. I used to have a blanket weed problem in my pond but since I started clearing the sludge out regularly and using barley straw in old tights, I haven't had a problem.
  • I've built several ponds and have never used a filter or barley straw. Barley straw does have some effect, naturally, but its use is promoted beyond its capabilities. For it to be effective, you actually need much more than the tiny (expensive) packs you get in some garden centres.  Important is to get plants established, and about 30 - 40% of the water surface covered (lily or another floating surface weed). The excess nutrients are then used up and sunlight onto the water is reduced, both of which events keep the alga in check.  You've only just re-done the pond, so it'll take time for the plants in it to get going, plus, we've had a lot of sunshine which will boost the blanket weed growth faster than any new planting can cope with, yet.  Give it time. HC

  • Thanks for all your advise.  I will leave it for a while and maybe try old tights and some real Barley straw and keep pulling it out daily.  Thanks again.

  • BizzieBBizzieB Posts: 885

    Thank you all image  reassuring advice Hortum-cretae

    Just posted thanks on a similiar thread where watercress was recommended with good results. 


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