Green water in ponds and aquarium tanks is a common problem.
The green water can end up like pea soup and you cannot even see the fishes.
Why does the water turn green?
Green water is caused by microscopic algae. The algae which is a living plant is so fine that
it goes through the filter media. Just like black coffee coming out of the coffee sock.
One way to get rid of it is to coagulate the microscopic algae spores into bigger lumps which can then be trapped and removed by cotton filter wool, sponge or other media.
But this is only a TEMPORARY solution.
The algae will build up again if the cause of the algae bloom is not eliminated.
Algae is a PLANT. Like all plants it needs SUNLIGHT (including artificial light), FOOD, AND Carbon dioxide (C02) to grow.
This process is called photosynthesis. A process which releases oxygen during the day when there is light and carbon dioxide when there is no light.
If any of the three ingredients is missing, the algae will die.
There is a PERMANENT solution.
And that is to culture enough nitrifying bacteria in the filter system to compete for the food which is the fish waste, decayed vegetation etc.
It is like a tug of war. More nitrifying bacteria you have in your pond or tank, your water will become clear indefinitely. Nitrifying bacteria also get rid of your toxic ammonia, nitrite which invariably come from fish urine, feces, and decayed matter.
Once the microscopic algae die the water becomes clear.
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