by Maya Savir – JustSpirulina
A small yard, balcony, windowsill or roof will be suitable.
Spirulina needs sunlight so any growing premise should be able to provide it. It is also important that the growing premise be able to provide shade, as direct sunlight may harm Spirulina, especially in its early stages.
Spirulina needs sunlight so it is preferable that the container in which it is grown be transparent.
Empty, clear soft drink or water bottles (at least 1.5 litre) are a good option.
Another option is a small pool or basin. These can be built using a variety of materials. It needs a construction – a frame which can be made of wood, metal, even sacks filled with sand or soil, and lining – for which greenhouse nylon 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.
When growing Spirulina in a pool or basin where there is no roof, a (removable) cover is needed for protection against rain, as rain will dilute the growing culture and alter pH level; and against sunlight, as direct sunlight may harm Spirulina, especially during its first stages, when it has not yet matured. Any board will do, as well as palm leaves or the same sheets used for lining the pool.
Quantity of bottles and pool measurements depend on the number of people expected to consume the Spirulina: approximately a bottle per each individual per day (meaning approximately 5 bottles per person); each square meter pool will provide 5g of harvested and pressed Spirulina a day.
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. Even contaminated water will do, as parasites, germs and viruses cannot survive this alkaline environment. It is important to note that excluded from this are water containing heavy metals, as Spirulina will absorb them.
The culture medium in which Spirulina is grown is highly alkaline, an environment that ensures Spirulina’s dominance, 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 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.
When Spirulina is ready for consumption, a filter device is needed for separating the Spirulina from the culture medium in which it grows.
Cloth with a density of 50 micron in diameter is a good solution. This kind of cloth is often a product of the printing industry and can be found anywhere screen printing (the most basic method of printing) is done.
A sheet of silk can be used as well.
The culture medium in which the Spirulina is grown consists of water and fertilizers.
If not available, almost every component can be substituted with natural ingredients that can be found in the local environment at minimal or no cost.
The following fertilizers are required:
Sodium Bicarbonate (NaHCO3) – Drinking Soda Powder which can be found at any market. If not available, the nutrients it provides can be found in tree ashes: tree ashes are mixed with water and kept in an open container so that the solution absorbs CO2 from the air. A week later, the liquid becomes a carbon extract with a pH level that should be 10.5.
Potassium Nitrate (KNO3) – can be substituted with urea (which is made up of ammonia and CO2), though it recommended for more experienced growers as its concentration in the medium must be kept low (below 60mg per liter); or with any nitrogen containing fertilizer, in which case potassium sulfate should be added.
Sodium Chloride (NaCl) – any cooking salt.
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). If not available, it can also be substituted with ashes of peals of bananas or papayas.
Iron Sulfate (FeSO4) – pentahydrate, not the type used for lawns. If not available, it can be substituted with an iron extract made by placing a few nails or bolts in a glass of lemon juice, vinegar or any sour liquid for a few days. Use 0.1 ml per litre.
Magnesium Sulfate (MgSO4) – pentahydrate.
* When growing Spirulina in pools a source of calcium must be added from lime, calcium chloride or gypsum. For quantities see section 3.6.
* In extreme, “survival” situations, nitrogen, phosphate, sulfate, sodium, potassium and magnesium can all be found in urine from persons in good health, not consuming medications or drugs. The iron that cannot be supplied by urine can be supplied by the iron extract described above.
It is not recommended to begin growing Spirulina using these substitutes, but once the Spirulina is mature and stable, these substitutes can replace the nutrients lost when harvesting Spirulina. If growing in bottles: use 5ml urine and 0.1ml for every litre. If growing in pools: for every 1K of harvested and pressed Spirulina add 15-20L urine and 100ml iron extract.
After initial administration, iron extract can be added once a week (very gradually and while stirring), but urine must be added daily.
* If fertilizer grade chemicals are used, they should be of the “soluble” or “crystallized” type, not of the “slow release”, granulated type.
* Micronutrients solution is not a requirement but will make harvesting easier and the medium reusable more times. It can be bought where Spirulina culture is sold. It can also be supplied upon request by Antenna Technologies (see appendix 4).
At least the quantity of a test tube is required to begin with.
A portion of strong and mature Spirulina (i.e. Spirulina that is ready for harvesting or multiplying) can be passed from one Spirulina grower to another so that the latter can start a new Spirulina culture at no cost.
Spirulina can also be bought. There are a number of Spirulina culture collections around the world that will send Spirulina by mail.
For contacts of Spirulina distributers see appendix 4.
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 not multiply and will ultimately die.
In order to maximize Spirulina exposure to sunlight, the water in which it is grown must be stirred.
Stirring can be done manually, using a stick or – better yet – a broom.
Another option is a pump, the simplest kind used for aquariums.
A funnel is used to pour liquids into bottles.
If not available, a devise can be improvised be rolling plastic, PVC or any other water resistant sheet.
The solution in which Spirulina is grown consists of water and fertilizers.
2.1.1. WEIGH AND MIX FERTILIZERS
The following measurements are for 1 litre water:
16g Sodium Bicarbonate (NaHCO3)
2g Potassium Nitrate (KNO3)
1g Sodium Chloride (NaCl)
0.1g Potassium Dihydrogenate Phosphate (KH2PO4) – comes as granules so needs to be crushed into powder.
0.1g Iron Sulfate (FeSO4)
0.1g Magnesium Sulfate (MgSO4) – may need to be crumbled.
* If not available, almost every component can be substituted (as specified in section 1.6).
* It is advisable to use gloves when coming in contact with these fertilizers, Potassium Dihydrogenate Phosphate (KH2PO4) in particular. If gloves are not available, it is advisable to use a spoon or any other means to avoid direct contact with skin.
2.1.2. ADD FERTILIZER MIX TO WATER
Stir the water and fertilizers until fertilizers are completely dissolved in the water.
The color of the growing culture should be a pail shade of yellow.
2.1.4. EXAMINE pH LEVEL OF GROWING CULTURE
Dip litmus paper in solution for 2-3 seconds.
Colors on litmus paper will change.
Compare colors on litmus paper to those on litmus paper box.
Growing culture should have a pH level of 8-8.5. If pH level is lower, add Sodium Bicarbonate. A higher level is fine. At pH 8-8.5 the growing culture is ready.
* After preparing growing culture a number of times, this stage of examining the pH level of the growing culture will not be necessary, as the color of the solution will be a sufficient indicator.
* It is advisable to first prepare the fertilizer mix and only then dissolve the mixture in water.
* The fertilizer mix can be prepared in advance and dissolved in water upon use. It is also possible to prepare the growing culture in advance (i.e. dissolve the fertilizer mix in water), in which case it is important to keep the growing culture in a closed container and in the shade.
2.2.1. ADD GROWING CULTURE TO SPIRULINA
Proportions should be, roughly, half Spirulina half growing culture.
Spirulina should be stirred every 2 to 4 hour so as to maximize exposure to sunlight. Having said that, it is important to note that during the first week or so, when the Spirulina is not yet dense in quantity, exposure to direct sunlight should be limited.
Bottles can be stirred in gentle, circular motions. It is advisable to close the bottle while stirring so no Spirulina is spilled, but it is important to reopen it immediately so that Spirulina gets the oxygen it needs.
2.2.3. ADD WATER
Liquid level in the bottle will lower within a day to a few days, depending on heat and humidity. It is important to “water” the Spirulina and keep liquid level constantly high.
2.2.4. EXAMINE pH LEVEL
The optimal pH level for Spirulina is 10-10.5.
After adding growing culture to Spirulina, pH level will begin to rise and reach the optimal 10-10.5 within a timeframe varying between a few days and a few weeks. A good indicator that pH level is rising is the growing density of Spirulina, which in its turn is indicated by the color of the liquid, which will become a darker and darker shade of green.
Examining pH level of is done in the manner as examining pH level of growing culture (section 2.1.4.):
126.96.36.199. DIP LITMUS PAPER IN LOQUID FOR 2-3 SECONDS.
188.8.131.52. COLORS ON LITMUS PAPER WILL CHANGE.
184.108.40.206. COMPARE COLORS ON LITMUS PAPER TO THOSE ON LITMUS PAPER BOX.
It is important to note that the more experienced the Spirulina grower is, the less he/she will need to rely on litmus paper. A look at the color of the liquid will be enough – the darker the green the stronger denser the Spirulina, meaning its pH level is at its optimum.
When pH level has reached 10-10.5, Spirulina is mature, which means it is ready for harvesting (for the purpose of consuming it) and/or multiplication (for the purpose of increasing its amount). Having said that, it is advisable that another week or so passes so Spirulina can become yet stronger and denser. During this week or so it is important to continue to stir the bottle and “water” the Spirulina.
Once Spirulina has reached maturity and stability, it is ready for multiplication (and harvesting, which will be discussed in section 2.4.).
In optimal conditions Spirulina multiplies itself within 24-48 hours. In less that optimal conditions it may take longer.
2.3.1. DIVIDE LIQUID CONTAINING SPIRULINA INTO TWO BOTTLES.
2.3.2. ADD GROWING CULTURE.
Proportions should be, roughly, half Spirulina half growing culture.
2.3.3. EXAMINE pH LEVEL.
Dividing Spirulina and adding growing culture will have lowered pH level. Within a few days to a few weeks it will again reach its optimal level of 10.10.5. and the liquid will again be darker as Spirulina grows stronger.
During this period, Spirulina needs to be tended to as it was during the first stage (section 2.2.), i.e. stirring and “watering”.
Examining pH level is done as it was done during the previous stage (section 2.2.4.).
When pH level has returned to 10-10.5, it is advisable to give it a week or so to further strengthen and stabilize and it is then ready for another cycle of multiplication (or for harvesting).
When Spirulina is mature and strong, it is ready for harvesting (or multiplying, as discussed in section 2.3.). Essentially, harvesting Spirulina means separating it from the growing culture.
Harvesting during morning hours is best for both nutritional and practical reasons.
2.4.1. HOLD CLOTH OVER A BUCKET, POT, OR ANY OTHER BASIN.
2.4.2. POUR LIQUID CONTAINING SPIRULINA ONTO CLOTH THAT IS USED AS FILTER.
Spirulina will remain on cloth.
Growing culture will be collected in bucket, pot or basin and can then be returned to bottle for reuse two or three times. After that it should be discarded and a fresh growing culture used.
* Do not discard used growing culture in sewage system. Do not pour it directly onto ground. It must be diluted with water (roughly 1:10) and can then be used as fertilizer for any garden or crop. Another option is placing used growing culture in an open basin in the sun. When the liquid has evaporated, the remaining dry sediment can be safely thrown away in a closed plastic bag.
2.4.3. REDUCE PIRULINA’S pH LEVEL.
The pH level in which Spirulina is grown is unhealthy for human consumption. To lower it to a healthy level (7pH), it is best to squeeze it to eliminate any remaining growing culture.
Press the filtering cloth containing the Spirulina evenly and gently. When the water drained out is green, stop squeezing.
If it is not possible to squeeze the Spirulina, another option (though less recommended) is to rinse it water.
The drained and pressed Spirulina should at this stage be similar in texture to paste.
Harvested Spirulina that is not consumed should be dried. In this form, it can be kept for months.
2.5.1. SPRED SPIRULINA ON NET
A net enables drying from top and bottom thus shortening time needed, but if it is not available, any other platform can be used.
Using finger, knife or spatula, spread Spirulina on net.
Another option is using a nylon bag with a small hole or a syringe to create thin Spirulina “noodles”.
If using an oven, dry at 40°c for 16 hours or at 60°c for 4 hours (the lower the temperature the more nutritional value).
If drying in the sun, 2 days should be sufficient.
Pools are a good option for growing Spirulina in larger quantities.
3.1.1. REMOVABLE COVER
A cover is needed for protection from rain, as rain will dilute the growing culture and alter pH level. It is also important when the pool is exposed to strong winds which carry dust and soil, as well as in cases where there are many insects.
The cover can be a board, palm leaves, or the same sheets used for lining the pool.
It is important to have more than one pool. Growing Spirulina in more than one container (be it a bottle or any kind of pool) minimizes the risk of unsuccessful Spirulina. If Spirulina in one of the containers is contaminated or not doing well for any other reason, there is always the other container.
The pool should be cleaned from sediment every six months.
When cleaning, the liquid containing the Spirulina is transferred to another pool, basin, or even pots and buckets.
Water and soap used for dishes are good for cleaning the pool.
3.1.4. MEASURMENTS OF POOL
Depth of pool should be approximately twice the depth of the culture in which Spirulina is grown.
In optimal conditions, growing culture should be 15-20 cm tall. That said, if the pool is transparent (glass for instance) it can be substantially taller.
As this manual is intended for growing Spirulina in communities in need, it is likely that in most cases conditions will be less than optimal. For this reason, it is recommended that Spirulina be grown in a culture that is 30-40 cm tall in a pool 60-80 cm tall. This will allow a “margin” of errors or imperfect conditions without causing harm to the harvest.
Follow the instructions for preparing growing culture for bottles (section 2.1.).
Multiply amount of growing culture according to the amount of Spirulina, i.e. for 20 litres Spirulina, prepare 20 litres growing culture.
Dissolving the fertilizers in water before adding the growing culture to the pool (as is the case in bottles) may be inconvenient in pools, as the quantities are larger. The fertilizers and water can be added to the pool separately. Given a few hours and some stirring, they will dissolve.
Follow the instructions for bottles (section 2.2.): Adding growing culture, stirring, adding water and examining pH level are the same, with the exception of the stirring devise.
Stirring in pools can be done manually, with a stick or – better yet – a broom (which stirs larger portions), or with a small pump (the kind used in fish aquariums).
Increasing the amount of Spirulina in a pool is similar to that of bottles (section 2.3.). The difference is that the liquid containing Spirulina is not divided between bottles and then growing culture added. Rather, pool measurements are increased and growing culture is added, which allows for Spirulina multiplication. This is done by placing a board or some other partition in the pool. This partition functions as a dam, and Spirulina is grown in the smaller area it creates. When Spirulina is mature and ready for multiplication, the partition is moved to create a larger and larger pool. When the pool has reached its full size, increasing the amount of Spirulina is a function of how much of it has been harvested for consumption.
Harvesting from a pool is similar to that of bottles (section 3.4.). Since quantities are larger, “framing” the filtering cloth within boards may ease the process and the frame can be held directly over the pool. It is important that 10 percent of the filtered growing culture be discarded (as described in section 3.4.2.). The rest can be returned to the pool. Growing culture is then added to compensate for the discarded liquid.
After harvesting, the nutrients that the Spirulina fed on must be replaced.
For every 1K of harvested, pressed Spirulina add:
350g potassium nitrate
15g Potassium Dihydrogenate Phosphate (or Diammonium phosphate or Monoammonium phosphate. As mentioned in section 3.1.6. phosforic acid can also be used, but is recommended for experienced growers, as it must be used with caution).
8g Potassium sulfate
8g Magnesium sulfate
3g Lime (or calcium chloride or gypsum)
1g Iron sulfate
* Sodium Bicarbonate is used when starting a Spirulina pool. Once mature, Spirulina can obtain the CO2 it needs from the air so there is no need to add sodium bicarbonate. This is important because sodium bicarbonate is the most expensive component. If, on the other hand, the pool is intended for a business (even small scale), sodium bicarbonate will supply Spirulina with CO2 it needs to enhance productivity. Another (cheaper) method of administering CO2 is with a gas cylinder (the kind used for making soda water) and a plastic bag. Place plastic bag on the pool, about 4 percent of the total area is sufficient. Connect a small tube to the gas cylinder and place it under the plastic bag. Let the CO2 bubble into the liquid.