Blanket weed blues

Blanketweed is a common problem in ponds, especially new ponds. There are various ways to get rid of it, but you should choose your plan of attack carefully.

Your UV clarifier won’t kill blanket weed because a UV can only “zap” algae that floats past the light and blacketweed usually attaches itself to the pond walls – it is not an algae that floats about like green water.

Blanketweed thrives of nitrates and phosphates which can be caused by over-feeding your fish. The uneaten fish food can give off phosphates and the fish waste can cause ammonia and nitrate.

Another factor for high nitrate and phosphate levels is “new pond syndrome” – before your pond has had chance to mature with beneficial bacteria, the tap water may be high in nitrates and phosphates. For this reason you should let your pond mature before introducing fish.

Some blanketweed treatments will kill off the algae but then leave you with dead blanket weed which then decomposes and gives off nitrate and phosphate…. guess what happens next….that’s right, an abundance of blanket weed!

If you don’t have a powerful enough filter for the size of your pond this can be another factor. So check the flow rate of the filter you have.

One of the best treatments for this kind of algae is Swell’s Control Blanket Weed, this easy-to-use treatment is comprised of beneficial bacteria to lower the nitrate and phosphate levels and also contains barley straw. When barley straw rots, the microbial process disrupts the algae.

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Georgina is a member of the Swell UK marketing team and has been keeping tropical fish for a number of years now. Her favourite fish being the stunning, male Siamese Fighting Fish. She is also looking to expand her existing collection to include keeping saltwater fish as well. Her other pets include Bengal cat, Walter, and Labrador and Rottweiler cross, Presley.


  • Peter North Posted 23/05/2017 at 6:02 pm | Permalink | Reply

    I have had a bad case of blanket weed but after clearing the long green slime with (blanket answer) I have been left with cloudy slightly greenish and gritty water. what would you recommend to clear this up as it has now been 4 weeks since the treatment was put in,
    I have about 6000 uk gals with a bottom drain and an EB60 bead filter system with midi sieve, hope you can help.
    Peter North. Norwich.

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