Algae doesn’t need the same water quality or conditions that plants and fish require. However, each species still has a set of conditions needed for rapid growth and profitable harvests. Most algae share a similar set of requirements, but they can vary between species and even within the same family. For example, heterotrophic algae can grow in complete darkness and rely on an alternative food source. Exploring the common requirements that most algae need for rapid growth will help you design your ponds properly.
Plenty of Sunlight or Artificial Lighting
Since almost all algae rely on photosynthesis to produce food for themselves, they also require plenty of light. Most algae need a minimum of 4 to 8 hours of bright and direct sunlight per day or the equivalent of it from artificial sources. Producing that many lumens of direct light costs more electricity than you might think, making it essential to use sunlight whenever possible. Since algae at the bottom of the pond can’t absorb sunlight like those at the surface, mixers are also necessary to tumble the tiny plants around and ensure even exposure.
Soluble Fertilizers
Some types of algae, including the cyanobacteria known as spirulina, require fertilizers to be added to the water to feed their growth. Chlorolla is one highly productive microalgae species that breaks with this tradition. It requires little to no soluble fertilizers. Algae generally needs some amount of nitrogen and a smaller amount of phosphorous to grow and reproduce rapidly. Nitrogen can be added from organic or synthetic sources, while phosphorous that is soluble enough for algae growth will only be available from a synthetic source.
Minerals
Even algae that don’t need a specific source of nitrogen or phosphorous will want a small amount of minerals mixed in with the water. Using a water supply that is naturally on the hard side can satisfy these requirements for most species including Chlorella. Some macroalgae and seaweed varieties need a high salinity since they’re ocean plants. Salt alone won’t support strong health, so don’t forget about the dissolved calcium and other minerals the ocean usually supplies for these plants.
Glucose for Heterotrophic Growth
If you’re planning to experiment with dark systems and algae varieties capable of heterotrophic growth, you’ll save a lot of money on electricity bills. In exchange for those savings, expect to pay for glucose solutions to feed your algae instead. This is an alternative system that uses glucose as the carbon source for food production inside the plant. Not all algae varieties are capable of this kind of production. Yet, some of the most interesting ones, with high commercial potential, grow fastest in this kind of arrangement.
Carbon Dioxide
As a plant, each algae organism draws in carbon dioxide and releases oxygen the same way any tree or shrub does on land. In fact, algae is responsible for a large percentage of the total oxygen in our environment due to the sheer amount that grows in various waterways. If there’s not enough dissolved carbon dioxide in the water supply, the algae will grow slowly. There’s no need to oxygenate the water like you would for fish. Instead, you may need a gas sparger that forces carbon dioxide bubbles throughout the pond to ensure each algae organism gets as much as its needs to grow.
General Good Water Quality
While algae are far less tied to specific pH levels or hardness than fish, they still need generally good water quality to grow well. Turbid water, in particular, is a problem since the reduction in light transmission greatly slows growth from photosynthesis. You definitely need to test and may need to treat the water you’re using to refill your algae ponds separately from the rest of the system.
With the right mix of carbon dioxide, temperature, light exposure, and fertilizer, any algae can grow practically anywhere in the world. Stick to native and local varieties unless you plan to profit enough to support expensive heating and lighting equipment.
