Ponds – Clean Water but Lots of Blanket Weed & Algae?

So you have treated your pond for Algae and have lovely clear water. Problem is, now you have another issue… blanket weed!

Why is this?

When you treat your pond with a UV filter, the algae in the pond dies, it then decomposes and turns into a fertiliser for the blanket weed to grow.

How do I treat this?

You can treat your pond with a number of treatments we have in store such as:

  • ‘Cloverleaf Blanket Weed Answer’
  • Colombo: ‘No More Blanket Weed’ or ‘Prevents Blanket Weed’
  • Tetra: ‘Algofin’
  • King British: ‘Barley Straw Extract’
  • ‘Barley Straw Net’ – Use one net per 1000 gallons (for smaller ponds you can cut the net in half & re-tie the ends) use one-half at a time and use until the straw has fully decomposed, then remove it. After two weeks replace with a new one.

Why Barley straw and how does it work?

When barley straw decomposes it releases photo toxins into the water, this kills Blanket Weed & Algae. Once the straw has started to release the chemical it will remain active until it has almost completely decomposed.

The straw should remain active for between four & six months, after which, its activity decreases rapidly.Despite the simplicity of the idea, experience has shown that there are a number of basic rules that must be followed to ensure the straw works successfully. It works best if it is held near to the surface where water movement is greatest, preferably near the filter outflow.

It is always preferable to have several small quantities of straw to a water body rather than a large one.Hay & green plant materials should not be used because they can release the nutrients which may increase the algal growth. They rot rapidly and may cause deoxygenation of the water (harmful to fish & other aquatic plants).

What about my other plants in the pond?

No direct effect of straw on aquatic vascular plants has been found in either the laboratory or field experiments.

Is Barley straw okay for my fish?

There is anecdotal evidence that in fish farms & fisheries, straw treatments may be associated with improved gill function, fish health & vigour.

What else can I do?

Make sure there is no lime being washed into the pond from concrete pavers or pointing. Even the smallest amount of lime can encourage green water algae.

Your pond should be at least 75% full of plants and the surface should be shaded with Lilly leaves.

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