Algae or Phytoplankton are microscopic plants. They are very tiny can't be seen by the naked eye, green color water is a sign of algae present.
Is Algae bad for Aquaponics ?
There are bad and good sides to Algae.
The good part are
1. They are a natural source of food to the fishes.
2. Like all plants, they produce oxygen with sunlight.
So what's the bad part about algae ?
1. Like all plants, they consume oxygen during the night.
2. They use nutrient from the water.
Most people just cover their tank or pond to ensure no algae present. However in my opinion if we could control algae using its good properties, we can have a better Aquaponics system.
Fish waste that exist in the water need oxygen to be broken down into nutrients, in normal fish pond, this rely heavily on oxygen found in the pond. If the amount of fish waste is too much, this breakdown process can cause depletion of oxygen and kill the fish.
Fish waste broken down are use by algae as nutrient and if there a lot of sunlight, in turn will produce more oxygen. This cycle continues throughout the day. At night is where the danger lies, Algae, Fishes and Microbes that breakdown fish waste will all compete for oxygen. If there is not enough, something will need to give way,, usually fish will die.
Early morning, is the time where oxygen content is at its lowest. During this time we should look at the fishes, whether they are gasping for air at the surface. If they are, then you have oxygen problem.
In Aquaponics, breakdown of fish waste to nutrient are done by organism in the water and growthbeds. They need oxygen to do this hence in Aquaponics setup, flood and drain system are employed to ensure oxygen are readily available to the organism.
Is algae good for Aquaponics ?
I would say yes, because it provide food for the fish. We need to understand how to control algae and benefit from it. One way to have enough oxygen in the ponds is to provide aeration, this will ensure fishes, algae and microorganism have enough oxygen to do their best for our setup.
To acheive this balance is the hard part, however with trial and error we should be able to make improvement in the system.