Green water (algal bloom)
Massive proliferation of suspended unicellular algae which makes the water green and opaque. Common in ponds and aquariums exposed to too much light.
Detailed explanation
Green water is caused by an explosive proliferation of phytoplankton (suspended unicellular algae). Unlike algae that grow on surfaces, these float in the water, making it opaque.
The causes are always the same: too much light (especially direct sunlight), too many nutrients (high nitrates and phosphates), little competition from plants or other algae.
In ponds it is an almost inevitable seasonal phenomenon. In spring the increase in hours of light and temperature triggers bloom.
The UV sterilizer is the most effective and quickest remedy. Single-celled algae pass through the UV tube and are killed by ultraviolet rays. In 3-7 days the water becomes clear again.
The alternatives include: total darkening of the aquarium due to 3-4 days (black-out), chemical flocculants that cause algae to precipitate, and phytoremediation with marsh plants in ponds.
In planted freshwater aquariums, green water is rare if the plants grow well. Plants compete with algae for nutrients and win when they are healthy.
Coralia Lab monitors this parameter with AI diagnostics. Tank Score alerts you when a value moves outside the recommended range for your aquarium.
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