top of page

Spirulina Growing FUNDAMENTALS

As described in the Requirements chapter, Spirulina needs sunlight, water, fertilizers and agitation - the practicalities of which will be explained hereafter.


It is important to have more than one pool (or container).

This minimizes the risk of large Spirulina loss in case of culture contamination. Redundancy is also important when cleaning pools.


Pool (or container) should be cleaned from sediment every 4 to 6 months (or sooner, if needed).

Spirulina is transferred from one pool to another. The empty pool is cleaned, and then the Spirulina is returned to the first pool. The same procedure is done with the second (and third, and so forth) pool.

Water and bleach are used for cleaning the pool or basin.


All tools that come in contact with the culture must be cleaned before and after each use.


Depth of pools should be approximately twice the depth of the culture in which Spirulina is grown.

Depth of culture should be approximately 20 cm.

Measurements of pools depend on available space and on the number of people expected to consume Spirulina. As noted above, each meter square will produce approximately 10 grams of fresh Spirulina.

2 pools of 2 meters x 2 meters are a reasonable beginning.


As noted above, the following is one of a variety of chemical environments that Spirulina can live in.

All Spirulina culture mediums are based on the Zarouk Medium and consist of the following elements:


  • Nitrogen, phosphorus and potassium in large quantities;

  • Sulfur, magnesium and calcium in smaller quantities;

  • And boron, chlorine, manganese, iron, zinc, copper, nickel, molybdenum in very small (micro) quantities. 


Weigh and mix fertilizers with water


The following measurements are for 1 liter water:

  1. 16g Sodium Bicarbonate (NaHCO3

  2. 2g Potassium Nitrate (KNO3)

  3. 1g Sodium Chloride (NaCl)

  4. 0.1g Potassium Dihydrogenate Phosphate (KH2PO4) – comes as granules so needs to be crushed into powder.

  5. 0.1g Iron Sulfate (FeSO4)

  6. 0.1g Magnesium Sulfate (MgSO4) – may need to be crumbled.

The color of the growing culture should be a pail shade of yellow.

  • It is advised to use gloves when coming in contact with these fertilizers, Potassium Dihydrogenate Phosphate (KH2PO4) in particular. If gloves are not available, it is advised to use a spoon or any other means to avoid direct contact with skin.

Measuring salts on Scales
Measuring salts on Scales 2
Mixed Salts and Minerals
Pouring mixed Salts and Minerals
Mixing Spirulina, Salts and Minerals

The Spirulina Growing Manual is also available in PDF


As in any agriculture crop, it is important to keep track of the status of the Spirulina and of the environment. This close monitoring will enable quality control, early detection of problems and continuous improvement in farming methods. It will also enable all caretakers of the Spirulina to share this knowledge. 

The crucial elements that need to be monitored are: temperature (of culture and of air), pH level, culture depth, radiation (amount of light), salinity, density.

Besides temperature of air in greenhouse and radiation (which will be the same for all pools or containers in it), these measurements should be taken and kept track of separately for each pool or container. Measurements should be taken twice a day.

Tools that come in contact with culture (thermometer, for instance) should be cleaned between pools, preferably with distilled water if available.

It is also advisable to monitor the amount of Spirulina that is harvested at each harvest (and for every pool).   


Spirulina's reproduction is asexual. Given the right conditions (temperature, lights, fertilizers, agitation) it doubles itself approximately every 48 hours.

When Spirulina is mature and dense (this can be estimated by the dark green color of the culture, with a microscope or with a graduated cylinder, as will be described in next section) it is ready for one of two procedures (which will also be described hereafter):

Increasing amount of Spirulina - This is done when the desired quantity of Spirulina has not yet been reached (usually in the first stages of establishing a Spirulina site);

Harvesting Spirulina - In order to consume it. Important also in order to renew Spirulina culture.

bottom of page