Understanding blanket weed

Owning a pond can be rewarding, but it also comes with its share of challenges. A notorious issue for pond owners is blanket weed, a type of algae that can proliferate rapidly if left unchecked. Not only is it unsightly, but it can also disrupt the delicate ecosystem you’ve worked hard to cultivate.

In this guide, we’ll look at the causes of blanket weed in your pond and what you can do to get rid of it.

What is blanket weed?

Blanket weed is a form of filamentous algae which will grow to carpet the surface of the pond and areas of flow (e.g. waterfalls). It can occur in different forms but is often described as clumps of green, hair-like strands that float on the water’s surface or submerged just beneath the surface.

This type of algae can create a thick mat that not only blocks sunlight from reaching your plants but also reduces oxygen levels in the water, which can harm fish and other wildlife. Not only does it make your pond look unattractive, but it can also upset the chemical imbalance of the water, which in turn can lead to further issues.

What causes blanket weed?

Several factors can cause excessive growth of Blanket Weed and, although an effective treatment will remove algae, the causative factors must be addressed to prevent further outbreaks.

1. Excess nutrients – While some nutrients are good for your pond, too many can be damaging, particularly nitrogen and phosphorus. These nutrients can form due to decaying plant matter and fish waste. When your pond collects these nutrients, it can create a rich environment for algae to thrive.
2. Excessive sunlight – Although sunlight is needed for pond life, too much of it can actually harm your pond. When ponds are left unshaded they can receive direct sunlight for prolonged periods, which can allow algae to grow.
3. Stagnant water – Your pond water needs proper circulation for it to remain healthy. If not, it could become stagnant, providing a breeding ground for algae and blanket weed.
4. High pH – Ponds need a pH level that is typically between 6.5 and 8.5 for optimal health. Anything above 8.5 can create an alkaline environment providing ideal conditions for blanket weed to grow. A high pH level can be caused by a few factors, such as fish waste, plant debris or poor filtration.

How to remove blanket weed from your pond

While blanket weed can quickly take over your pond, there are a few ways in which you can remove it:

Use treatments

One of the easiest ways to get rid of blanket weed is by using a specifically designed water treatment – such as Clean Pond Pods, Pond Blanketweed Algaway, or Pond Balance. These treatments effectively remove blanket weed and string algae from your pond, and at the same time, encourage lush plant growth.

Blanket weed can take up to four weeks to clear, so persevere with treatment. Once it has cleared, continue treating regularly to maintain the active ingredients that will prevent re-growth.

Most treatments are safe for your fish, so you won’t have to worry about it impacting your fish or having to remove them from the pond.

Add floating plants

You may benefit from adding floating plants to protect your pond from excess sunlight. For example, use lilies and water soldiers to cover up to 50% of the pond surface area or use planting around the pond to create areas of shade across your pond.

You do not want to completely shade the pond as this will discourage good plant growth, however finding a balance could reduce the recurrence of blanket weed.

Control nutrient levels

If there are more nutrients than your existing pond plants, it can stimulate algae growth. Nutrient levels can be controlled by encouraging plenty of healthy fast-growing pond plants and regularly removing waste and sludge from the pond.

Check your pond filter

Your pond’s filter is the last line of defence against excessive algae growth. A good filter will work to remove any debris and excess nutrients from the water. However, if hindered due to a clog or from wear and tear, it will be less effective. Regularly check and clean your filter to make sure it performs at optimal performance to keep your water clean.

If your filter has a blockage, you can treat your pond with Sludge Buster to help break down waste.

Remove manually

If all else fails, you can remove smaller patches of blanket weed using a net. Be sure to dispose of the algae once removed to prevent it from decomposing back into the pond.

How to prevent future blanket weed growth

Other areas to consider to help prevent further outbreaks and aid treatment:

• Test water regularly (high nitrate levels will encourage algal blooms)
• Keeping plants healthy by feeding with Flora Boost
• Using preventative products like Clean Pond Pods, Sludge Buster or Bioactive Sludge Control once a month to steadily break down waste
• Clean your pond regularly, especially fish waste, plant debris, and any other organic matter

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