A beautiful garden pond can be the centrepiece of your outdoor space—but when algae starts to take over, that crystal-clear water can quickly turn into a murky green mess. At Perfect Aquatics, we regularly help pond owners manage and prevent algae growth with expert advice and quality products.
In this guide, we’ll explain what causes algae in your pond, the types of algae you might encounter, and—most importantly—how to prevent it from taking over.
What Causes Algae in Ponds?
Algae thrives in water when the conditions are right:
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Excess nutrients – from fish waste, uneaten food, or fertiliser runoff
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Sunlight – especially in shallow, unshaded ponds
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Stagnant water – poor circulation helps algae flourish
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Warm temperatures – algae blooms are more common in spring and summer
Types of Pond Algae You Might Encounter
1. Green Water (Planktonic Algae)
Turns the water into a green, cloudy soup—impossible to remove with nets.
2. String Algae (Blanketweed)
Forms long, slimy strands that cling to rocks, plants, and equipment.
3. Filamentous Algae
Creates floating mats or coats pond surfaces with a thick green layer.
Top Tips to Prevent Algae Growth in Your Pond
1. Shade Your Pond
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Add floating plants like Water Lilies
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Install a pergola or shade sail for partial coverage
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Use marginal plants like Iris or Water Forget-me-nots
2. Reduce Nutrient Build-Up
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Don’t overfeed fish—only what they eat in 2 minutes
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Skim out uneaten food, leaves, and sludge regularly
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Keep lawn fertilisers and runoff away from pond edges
3. Use Oxygenating and Floating Plants
Plants help absorb excess nutrients:
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Hornwort or Water Crowfoot oxygenators
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Water lettuce or Floating lilies for shade
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Marginal plants to create a natural filter
4. Keep Fish Stocking in Check
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Don’t overcrowd—check stocking guides for your pond size
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Use a high-performance pond filter like PondXpert MultiChamber Filters
5. Install a UV Clarifier
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A UV clarifier kills green water algae quickly and safely
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Perfect for spring and summer use
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Browse our full range of UV Clarifiers
6. Improve Water Circulation
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Add a reliable pond pump like PondXpert MightyMite
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Consider waterfalls or fountains for extra movement
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Use an air pump to increase oxygen levels, especially in summer
7. Use Safe Algae Treatments 🧪
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Barley straw extract for a natural long-term solution
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Blanketweed controllers for targeted control
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Bacteria-based pond clarifiers to improve biological balance
Ongoing Pond Maintenance
Keeping algae at bay is about balance. Be sure to:
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Test water regularly for nitrates and ammonia
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Clean filters and pumps monthly
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Remove decaying plant matter and sludge from the bottom of the pond
Need Help Beating Pond Algae?
At Perfect Aquatics, we’ve got everything you need to prevent algae and keep your pond healthy and crystal-clear, from UV clarifiers and algae treatments to oxygenating plants and pumps.
Visit our Bedfordshire store or explore our full range of pond care products online.