Spirulina Growing


Spirulina is grown in water and does not come in contact with land. It requires a pool or a container which can be placed in a yard or on a balcony, windowsill or roof.

Spirulina needs sunlight. 350 microeinstein is the most suitable level for Spirulina.

It is also important that the growing premise be able to provide shade, as direct sunlight may harm Spirulina, especially in its early stages. A removable cover can provide the shade needed.


Spirulina is grown in water, in containers or pools that are relatively shallow.

Containers (such as aquariums) can be made of plastic or glass (note that glass is less practical as it breaks easily). Spirulina needs sunlight so a transparent container is a good way to increase exposure.

Pools can be built using a variety of materials. They are usually built from a construction – a frame which can be made of wood, metal, even sacks filled with sand or soil; and lining – for which greenhouse tarp can be used, as well as any sheet of rubber or HDPE (High-density polyethylene). Generally speaking, plastics that are polyethylene based are the best option as there are no known health hazards related to their use.

Cement is not recommended, unless it is lined with greenhouse tarp in a way that it does not come in direct contact with the Spirulina.

Pool measurements depend on the number of people expected to consume the Spirulina: Each square meter pool will provide approximately 10g of harvested and pressed Spirulina a day.

A greenhouse is needed to protect Spirulina from rain, as rain will dilute the growing culture and alter pH level; From dust and sand, as dust and sand tangles in the Spirulina making it heavy and causing it to sink to the bottom where it is less exposed to light; From flies and insects; And from strong sunlight, as direct sunlight may harm Spirulina, especially during its first stages, when it has not yet matured. 


Spirulina is grown in a culture medium that is made of water and fertilizers.

Due to the high pH of this culture medium, Spirulina has almost no competitors. This means that it is not “fussy” regarding the water it needs: drinking water, brackish water, water from a natural body of water or rain water can be used. Almost all parasites, germs and viruses cannot survive the alkaline environment in which Spirulina strives.


It is important to note that excluded from this are water containing heavy metals, as Spirulina will absorb them.


The culture medium in which the Spirulina is grown consists of water and fertilizers. The specific 'recipe' can vary according to environment, type of Spirulina and availability of fertilizers. All 'recipes' are a variation of the Zarouk Medium defined in 1966 and it should be the reference for Spirulina farmers that want to experiment with the culture medium.

The following fertilizers are required:

  1. Sodium Bicarbonate (NaHCO3) - Drinking soda powder which can be found at any market.

  2. Potassium Nitrate (KNO3) - Can be substituted with urea (which is made up of ammonia and CO2), though it is recommended for more experienced growers as its concentration in the medium must be kept low (below 60 mg per liter); Or with any nitrogen containing fertilizer, in which case potassium sulfate should be added.

  3. Sodium Chloride (NaCl) - Any cooking salt.

  4. Potassium Dihydrogenate Phosphate (KH2PO4) - Can be substituted with any agricultural phosphate (Diammonium phosphate or Monoammonium phosphate; Phosforic acid can also be used but is recommended for experienced growers, as it must be used with caution).

  5. Iron Sulfate (FeSO4) - Pentahydrate, not the type used for lawns.

  6. Magnesium Sulfate (MgSO4) - Pentahydrate.

  • When growing Spirulina in pools, a source of calcium must be added from lime, calcium chloride or gypsum. 

  • If fertilizer grade chemicals are used, they should be of the “soluble” or “crystallized” type, not of the “slow release”, granulated type.

  • Fertilizers should be of food grade quality, at least.

Micronutrients solution is not a necessity, but it will enhance the nutritional value of the Spirulina and will enable easier harvesting. 


At least the quantity of a test tube is required to begin with. A few jerrycans will make the beginning easier.

A portion of strong and mature LIVE Spirulina (i.e. Spirulina that is ready for harvesting or multiplying) can be purchased - or better yet - passed from one Spirulina grower to another so that the latter can start a new Spirulina culture.

Spirulina can also be bought. There are a number of Spirulina culture collections around the world that will send Spirulina by mail.

Mineral Grinding
Grounded Mineral for spirulina
Grounded Mineral with water
Litmus test
Litmus test results
Spirulina Drying Device
Clean filtration cloth
Clean net for drying Spirulina

LITMUS PAPER (or any other method for examining pH)

The culture medium in which Spirulina is grown is highly alkaline, an environment that ensures Spirulina’s dominance and protection from most contaminators, as the vast majority of parasites, germs and viruses cannot survive it.


The pH level of the growing culture should be maintained at 10-10.5.

Though it can be done using sophisticated laboratory equipment, the easiest and cheapest method of examining pH level is done by dipping (for 2-3 seconds) litmus paper in the culture medium containing the Spirulina: The colors of the paper will change. Comparing the colors of the paper to the scale on the litmus paper box will indicate the pH level of the culture medium.

Litmus paper can be found at school labs and at stores that sell aquariums.


Harvesting Spirulina is essentially separating it from the culture medium in which it grows.


A filter device is used.

Cloth with a density of 30-40 microns in diameter made of polypropylene, nylon or polyesteris a good solution. 


Spirulina tends to gather at the top of the growing culture, where sunlight exposure is maximal. Due to this, Spirulina that cannot reach the top, will ultimately die.

In order to maximize Spirulina exposure to sunlight, the water in which it is grown must be agitated so that all Spirulina filaments are exposed to sunlight.

Agitating can be done manually, using a stick or – better yet – a broom (both must be cleaned before use). This should be done gently, in circular motions that maintain the same direction (clockwise or counter clockwise).

Another option is a small pump. The simplest kind used for aquariums will do.


A microscope will enable close inspection of the culture.


The cleanest possible environment is needed to grow Spirulina. This means that all caretakers must be gloved when tending to the Spirulina.