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How to grow Spirulina platensis at home

The goal of this guide is to teach the reader how to grow his/her own Spirulina platensis at home. By following our simple instructions you should be ready to harvest your Spirulina in about 2-3 weeks. We will also talk about optional equipment and discuss different growth mediums which can affect nutritional properties of your Spirulina culture.

  • Improper setup or use of CO2 Injection Systems can cause property damage, serious personal injury or dealth!
  • Do not consume Spirulina culture water as it is very alkaline and contains chemicals not suitable for human consumption!
  • Thoroughly wash harvested Spirulina under running water for at least 1 minute before using it for human consumption!
  • We advise against storing freshly harvested Spirulina. Harvest as much as you need for your use or dehydrate/freeze dry for future use. Refrigerate between 34-39°F (1-4°C) for no more than 3 days. Discard after 3 days, if foul smell is detected or if Spirulina changes color to blue! Consuming spoiled Spirulina can cause severe poisoning

Important Notes
  • Some "How to" guides advise not to use artificial lighting when growing Spirulina and simply go with the window light, however, fluorescent lighting is a requirement of our guide unless you can provide your culture with 16 hours of direct sun exposure combined with 8 hours of darkness. “Window” setups can be unreliable and produce low biomass cultures. Using artificial lighting (6500⁰K) will guarantee you steady results.
  • We suggest only using deionized/distilled/reverse osmosis water to make Spirulina culture growth medium solution. Spirulina species are known to readily absorb and accumulate heavy metals from their surroundings so this is something you definitely don't want if you are growing it as aquafeed or for human consumption.
  • Always purchase and use growth mediums specifically designed for Spirulina species. More popular mediums include Zarrouk's SM, Schlösser SMM and RM6. Zarrouk's SM is one of the oldest and proven mediums designed to achieve high biomass, better β-carotene synthesis and increased antioxidant potential of all Spirulina species. We are specifically advising against using Guillard's f/2 medium (which was designed for marine microalgae) to grow any of the Spirulina species. Using Guillard's f/2 medium can produce nutritionally deficient cultures and other unexpected results.

Hardware and Eqipment
Item Required Where to Buy Avg. Price AT 10G Grow Kit1
10 Gallon Aquarium Tank Yes Petco $19.99 No
50W Aquarium Heater Yes Varies $12.99 Yes
Digital Aquarium Thermometer with a probe Yes Varies $7.99 Yes
10 Gallon Aquarium Air Pump Yes Varies $9.99 Yes
Flexible Airline Tubing (ID2: 3/16") Yes Varies $5.99 Yes
Rigid Airline Tubing (OD3: 3/16") Yes Varies $5.99 Yes
2-Light 2 ft Fluorescent Fixture Yes Home Depot $19.96 No
2 x 6,500K 24" T8 17W Bulbs Yes Varies $7.99 No
Hydrofarm 15 Amp/1725 Watt AC Timer Yes Hydrofarm $14.99 Yes
Spirulina Starter Culture Yes Algoid Technologies $19.99 Yes
Culture Growth Medium Yes Algoid Technologies $39.99 Yes
Total (required): $165.86
80GPH (gallons per hour) Water Pump with 1/2" OD outlet Optional Varies $12.99 Optional
Flexible Airline Tubing (ID: 1/2") Optional Algoid Technologies $5.99 Optional
200 micron Mesh/Strainer Optional Varies $7.50 No
LED Grow Lights Optional Varies $29.99 - $159.99 No
CO2 Injection System Optional Varies $199.99 + No
CO2 Monitoring System Optional Varies $999.99 + No
Microscope Optional Varies $59.99 + No
Apollo 14 8-Outlet Power Strip with 24 Hour Timer Optional Titan Controls $22.99 + No

1 Indicates if an item is included in Algoid Technologies Spirulina 10G Grow Kit (see below)
2 Inside Diameter
3 Outside Diameter

Preparation and Setup
  • Place 10G aquarium tank on a flat sturdy surface capable of supporting at least 100 lbs / 45 kg
  • Set water heater dial to to 30℃ / 86℉ and install it inside the aquarium in the middle of the longer side of the tank. Do not connect power cord to AC outlet yet! Make sure that the water temeprature in your aquarium does not flactuate more than 1℃ / 2℉ and never goes above 35℃ / 95℉!
  • Attach the suction cup located near the water thermometer's probe inside the aquarium in the middle of the longer side opposite of water heater. Attach the suction cup located near the thermometer's LCD display to the outside of the aquarium tank
  • Fill the aquarium with 10 gallons of deionized/reverse osmosis/distilled water and connect water heater's power cord to AC outlet
  • Add Zarrouk's SM growth medium to the aquarium and mix well. Our version of Zarrouk's SM concentrate does not include sodium bicarbonate (baking soda) and common table salt so you will need to add 180 grams of baking soda and 10 grams of common table/sea salt. We highly recommend Arm & Hammer but you can use any brand you like just make sure that it is pure sodium bicarbonate (NaHCO₃). If you did not purchase Zarrouk's SM growth medium from us you will have to contact the manufacturer of your growth medium for further instructions on how to create a working culture solution
  • Secure the lighting fixture about 1 ft directly above the rim of the tank, install the bulbs and plug the power cord into AC timer's outlet. We recommend 16 hours of Light and 8 hours of Dark (L/D cycle) every day to achieve maximum biomass and the timer included in our Spirulina Growing Kit is already setup for this L/D cycle. If you purchased your AC timer elsewhere please install it according to manufacturer's instructions.
  • If you have purchased one of our kits, the aeration system will be ready to be used. Simply drop the end of the rigid plastic tubing into the aquarium and connect air pump's power cord to AC outlet. If you purchased your aeration set elsewhere please install it according to manufacturer's instructions. Aeration rate must be adequate enough to keep entire culture constantly circulating in the tank, which ensures that your cultrue receives enough light exposure. We do not recommend using any types of diffusers as they might slow down aeration rates.
  • You are now ready to add Spirulina Starter Culture to your tank. In order to avoid culture shock make sure the temperature of the Starter Culture and water in your tank is within 1℃ / 2℉ degrees. If not, make sure to gently raise or lower Starter Culture's temperature to match the temerature of water in the aquarium.
  • Add Starter Culture to the tank and get ready to wait anywhere from 2 to 4 weeks for the culture to propagate and become dense enough for harvesting.

Growth and Harvesting
  • You should monitor your culture for contamination and count cells on a regular bases, and the only proper way to accomplish this task is by the use of a microscope. Spirulina cells are large enough (200-800 microns long) and do not require very powerful magnification which should keep the microscope costs to a minimum. You will also need a cell counting chamber and we suggest using hemocytometer (Neubauer chamber) or Sedgewick-Rafter counting chamber.
  • Following is an example of how to count Spirulina using hemocytometer (Neubauer chamber). Set your microscope to 40X magnification and count fillaments found in all 9 squares of the counting chamber, multiply that number by 10,000 and divide by 9. Click here to see the picture of hemocytometer with Spirulina platensis fillaments (organisms) in its counting chamber. Start counting in the upper-right corner and keep counting fillaments in all squares following the red line. There are 15 fillaments in that picture so using the above mentioned formula we can find the amount of fillaments in 1 ml:

    (15 * 10,000) / 9 = 16,667 fillaments/ml

    Start counting fillaments a few days after adding Starter Culture to the tank and log your findings to see how your culture is progressing. If you no longer see daily increases in cell counts it means that you've reached the maximum biomass your setup will be able to produce. And this usually also means that you are ready to harvest.
  • The other way to know if you are ready to harvest your Spirulina culture is by the use of a Secchi disk. When Secchi is 3 cm or less you are ready to harvest.
  • Healthy Spirulina culture should have a pH of about 10 (+/- 0.5). We suggest monitoring pH at least two or 3 times per week while starting a new culture and once per week once you have an established culture. A drop in pH to below 9 or raise above 11 can severely inhibit growth or even crash your culture. In that case harvest as much Spirulina from your tank as you can and restart the culture using brand new growth medium and clean water.
  • Another major maintenance task will be replacing water loss due to evaporation and during harvest. Higher temperatures of Spirulina cultures facilitate excessive water loss due to evaporation and that is why we highly recommend the use of an aquarium cover. Spirulina growth mediums are not cheap and excessive water loss can substantially increase your maintenance costs.
    To calculate the precise amount of water in liters you will need to measure the waterline distance Wd (in centimeters) from the top rim of the tank to the current waterline level (see example below) and multiply that number by your tank's Sn (see example below).


    Length (L): 50 cm
    Width (W): 25 cm
    Sn: To find any tank's Sn you simply mutiply length by width and divide that number by 1,000

    Sn = (L * W) / 1,000
    Sn = (50 * 25) / 1,000 = 1,250 / 1,000 = 1.25
    Wd: 1.8 cm
    Water (liters): Water Required = Sn * Wd
    Water Required = 1.25 * 1.8 = 2.25 liters

    As you can see from this example the amount of water required to fill the aquarium is 2.25 liters. Add required amount of growth medium to 2.25 liters of distilled/deionized water (dH2O) to make a working solution and add it to your tank.

    WARNING: Never add fresh water directly to your tank!
  • To harvest Spirulina attach one end of plastic tubing to the water pump and submerse the water pump below the waterline. Use a rubber band to secure 200 micron mesh/strainer to the other end of the plastic tubing but make sure to leave sufficient space between the end of the tube and the mesh for the Spirulina to colect. Place the end with the mesh above the aquarium so water can be re-circulated back into the tank, turn water pump on and harvest as mush Spirulina as you need. Turn off the pump once you have required amount of Spirulina and squeeze as much water from the harvested culture as you can back into the tank. Don't forget to thoroughly wash harvested Spirulina and it's ready for your use.

Optional LED Lighting and CO2 Equipment
  • Addition of an LED grow-light system can substantially improve your biomass production. Extensive studies done by Wang, Fu and Liu in 2007 indicate that Spirulina grown under red light exhibits the highest specific growth rate. Blue light is the least effective in conversion of light to biomass. We suggest looking for grow-light fixtures/systems that provide combination of mostly red, white and blue light.
  • Maximum Spirulina biomass production can only be achieved with the use of a CO2 injection system but such systems can be costly and dangerous. Since the highest growth rate of Spirulina species occurs when supplied air contains about 8% of CO2, levels that can quickly fill an enclosed space with dangerous levels of the gas, the exhaust from such a system will have to be controlled. Supplying less than 6% of carbon dioxide produces the same biomass as the system without any CO2 supplimentation.
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