Grow Spirulina at Home: Complete Instructable


If you want to get your hands wet with Spirulina cultivation, this Instructable will guide you step by step. The key is to use food grade materials and nutrients to keep your supply safe.

Glass bioreactor are the easiest way of maintaining an indoor algae farm. Your space is usually warm and if you put it in a sun facing window it will have plenty of sun.

Step 1: Hardware

To grow Spirulina at home you are going to need some hardware to optimize and automize the process. Most of it is readily available at your local pet or fish store.

Picture of Hardware
Picture of Hardware
Picture of Hardware

10-20 Gallon Aquarium Tank
Air Pump
Air Line
Food Grade Harvesting tube
Ph Strips
Harvesting Cloth (50 micron filter cloth) 

The only thing that you will need to get from a specific source is your initial spirulina culture. 

Step 2: Tank setup

Find a south facing window for your tank. You can either use a table to place tank, or you can place a piece of wood on the window sill to make a shelf for the tank. Place tank on top. You can also grow spirulina in a greenhouse!

Step 3: Medium

Picture of Medium
Picture of Medium

The growing medium is the water solution that spirulina can grow best in. Since spirulina grows in alkaline environments, you have to make your water alkaline. This can be done by adding 16 grams/liter of sodium bicarbonate to non-chlorinated  water along with other nutrients: Ammonium Phosphate, Sea Salt, Potassium Nitrate. The most important of those is of course the sodium bicarbonate that creates an environments that resembles the ash lakes in nature in which spirulina grows.
To simplify the process, you can buy these nutrients pre mixed like I did. 

2.5 Gallons of non-chlorinated water along with 1 of a cup of pre-mixed nutrients is the recommended amount to start the culture.

At this point you can add Chelated Iron. It completes the nutritional needs of spirulina. Iron deficiencies are noticeable, just as they are in plants. Slight yellow shade is an indicator of iron deficiency.

Step 4: Adding culture

Picture of Adding Your Culture

Once your starter powder has dissolved and your water has reached room temperature or higher, you can now add spirulina to the medium. Adding spirulina to cold water can shock it, its like taking a cold shower! Only pour in 3/4 of your bottle so that you may have some in reserve in case anything happens to your first culture!

Step 5: Mark water level and put cover

Once your starter powder has dissolved and your water has reached room temperature or higher, you can now add spirulina to the medium. Adding spirulina to cold water can shock it, its like taking a cold shower! Only pour in 3/4 of your bottle so that you may have some in reserve in case anything happens to your first culture!

Adding a glass or plastic cover can decrease the amount of evaporation and help keep in the heat at night. This will also prevent contamition from any airbourne organisms. 

Step 6: Grow and repeat

This is where spirulina will begin to use the sun, CO2 from the air and the nutrients you added! Its nice to know that CO2 sequestration helps the environment AND it feeds your spirulina, which will feed you! In a time lapse anywhere between a few weeks and a month, it will begin to get more populated.

Repeat the previous steps to double your culture: Add another 2.5 gallons with Starter and Iron. Do this until your tank is full. If your culture is a good performer you can add 5 gallons at a time! Once your culture is well populated it replicates far quicker. In ideal conditions, it replicates (doubles) every three days! Much faster than most plants and it can do it year round!

You can now officially can call yourself a spirulina Farmer! Take a moment to understand the monumental significance of this! Spirulina superfood is being produced in your own home in an environmentally friendly way that does not require transportation, excessive water, and does not create runoff like most commercial plants! A pat in the back is well deserved!

Step 7: Testing culture

Picture of Harvesting Safety

You are just a few steps away from easy harvesting. Over the last two years of research and development, I have been eating spirulina with healthy outcomes. To replicate that, you just need to follow simple steps. Spirulina has an advantageous characteristic that allows it to grow in highly alkaline environments, meaning pH levels of 10 and above. This dramatically decreases the chances of foreign organisms growing your culture because they just can't survive in that kind of alkalinity. To safely harvest you simply have to wait for your culture to reach an approximate pH level of 10 using readily available pH strips.

Step 8:Harvesting

Once at the safe pH level you can set up your Integrated Harvesting Tube. It is important to only use a material that meets FDA standards because you want to use safe food grade elements in your spirulina farm. I got my kit from
Once you open the valve leading to the harvesting tube, fluid should begin to rise and flow.
You can now tie your harvesting cloth to the end of the tube with a rubber band to catch the spirulina flowing through the tube while letting the clear medium flow back into the tank. It is recommended to harvest 1/3 of the culture to allow it to repulate within a day or two. This way you can continually harvest as long as you keep feeding it nutrients.

Step 7: Feeding

As the spirulina grows, it consumes the nutrients you added. You simply need to add nutrients. For every tablespoon of live spirulina harvested you need to add a teaspoon of the following nutrient mix. Here are the weights to make one batch of mix nutrients: 1.4 KG of saltpeter, 50 grams of ammonium phospahte, 30 grams of potassium sulfate and 20 grams of epsom salt. Add a half dripper of Chelated Iron for every few tablespoons harvested. Thats it.

Step 15: Quality Control

Spirulina is safe to grow by the fact that its medium is highly alkaline so few other organisms grow in that environment. At the same time it is really fun and ensuring to do some quality control by getting hold of an affordable microscope and viewing your culture. Amazon is a great place to get a cheap microscope that will be more than enough for this task. This will really make you appreciate the little algae that you are consuming. Below you can see that only spirulina is growing in the culture. You could also buy a usb microscope camera to make your own video and documentation.