Growing Spirulina at home, made simple

September 9, 2008

I got interested in the idea of growing Spirulina at home after I obtained a breeding pair of Bristlenose Pleco’s.  What better food source than fresh Spirulina, I thought to myself.  I wondered around Google for days, which turned into weeks, then months.  No where could I find a single source that could easily explain how to grow Spirulina at home.
What is Spirulina?  
“This microalgae is 60% all-vegetable protein, rich in beta carotene, iron, vitamin B-12 and the rare essential fatty acid, GLA. It offers a striking profile of vitamins, minerals and phytonutrents. Scientific studies show remarkable health benefits.”
That’s fine & dandy, but I only want to grow it to feed to my pleco’s.  After spending month’s online reading technical scientific journals, learning chemestry (thought that was it after High School), and reviewing commercial grower patents, sales pitches, and documentaries, I have compiled all the knowledge needed to grow spirulina at home.  
If you are interested in growing Spirulina at home, I hope you find this method useful…
Like many freshwater algaes, spirulina has a wide range of PH’s in which it can grow. In fact, spirulina can be grown from a range of 3.5 up to, and above a pH of 10. Without having access to labratory conditions, it seems nearly impossible to just grow spirulina, and no other algae in the same water.  What I discover is if grown in Distilled Water, and no other algae is present in the water then your almost guarenteed, spirulina will be the only algae present.
Almost is not good enough.  After reading a scientific journal from 1979, I found an experiment done in france where spirulina troughs were exposed to the air.  To keep other forms of algae out of the growing spirulina exposed to the elements, the growers raised the pH of the water above 8.6 pH.  It seems as though no other algae will grow above a pH of 8.5
To review, the base for growing spirulina is Distilled water.  And to get the pH above 8.6, I recommend using a product named “PH UP!” & use pH test strips for a range up 8.6 pH.  No test strips are available for public sale above 8.6. You’ll have to guesstimate.
What’s next?  We need to know the ideal teperature for growing spirulina. Spirulina grows best at 86 degrees F.  Above 92, the algae cannot photosynthesize sun light and becomes weak and looses vicosity.  Any temprature below 82 degrees F and the algae continues to grow, just not at a maximium rate.  86 degrees F is ideal.  The one stable environment which can maintain this steady temperature and is readily available in the home is an aquarium.
We can’t just dump “PH UP!” into an aquarium filled with distilled water and raise the temperature to 86 degrees F and grow spirulina.  It would be quite an expense in distilled water and chemicals (PH UP!).  Instead, we need to consider the requirement I have not mentioned yet.  That is, spirulina needs to be stirred in order to expose each piece of fine weave of the algae to as much light as possible.  What we need, and what I’ve seen some labratories use are “Growing Tubes”.  
I’ll give you a quick run down of my version of “Growing Tubes”, both in expensive and easy to build in a day.  I went to Home Depot and bought a 1″inch wide, 8’feet long clear tube used for protecting flourescent lights in case of breaking. Also, I bought 90 degree angle 1″inch to 1/2″inch pcv pipe elbows (1/2″ screw in female) (10 items) and also got 1/2″inch screw in male plugs (10 items).  I cut the clear plastic tube into five equal sizes (18″inches each).  I filed down the 1″inch elbows, until they fit snuggly into the clear tube ends.  Drilled a hole, small enough for air line tubing to be pushed through, into the male plugs.
So when assembled end to end, a “Growing tube” would look like this: 1 Male plug screwed into one 1/2″inch elbow.  The other end of the 1/2″inch elbow is 1″ wide and fits into the 1″inch wide plastic tube.  The other end of the plastic tube looks the same way.  Now all that is needed is to use non-toxic silicon to make the air line feeding in both ends air tight.  Oh, and one side of the air line inside the elbow will need an air stone attached to produce small bubbles.  That’s it!  For about $18 you can build five “Growing Tubes”.  The growing tubes will be housed in your aquarium, and will maintain a steady temperature without receiving or giving containmination to it’s environment.  I was considering keeping Misquito Fish in this same aquarium, since they can live in temeratures up to 92 degrees.
To allow the spirulina algae to grow under the best conditions, and satisfy the need for “Stirring”, CO2 will be pumped into the “Growing Tubes”. Last, the algae needs nutritional a suppliment to grow. I found 2 solutions used in labratories for growing spirulina. Solution A & Solution B.  They need to be kept seperate for storage purposes, and should only be combined when mixing your solution in the growing tubes.  A cap full from each container is enough per 1 gallon of distilled water.
Ok, so where does the starter solution come from?  We can’t use store bought spirulina power, because it was been “Deactived” to keep it from going bad.  Commercially, the spirulina is raised to a temperature of 120 degrees F to “deactivate” it. Another alternative for storage is freezing it, but it only keeps for 6 months using this method and no such format is available for public sale. 
The gold mine find was stumbling onto Univeristy of Texas web site (  They are the largest publicly available supplier of algae strains in the world.  There are a few other one off labratories that will sell live spirulina to the public, but university of texas has several strains.  I found that “Spirulina sp.” is the same strain used commercially for human consumption.  If it’s good enough for me, I bet the pleco’s will love it!.
It takes approximately 90 days to grow spirulina in “Growing tubes”. Harvest the spirtulina by dumping the contents of the “growing tubes” into 50 micron wide cloth.  The particals of spirulina that pass through the 50 micron cloth are young enough to be your starter for your next culture, or 90 day cycle.  To lower the pH of the 8.6+ spirulina, all that is needed it to squeeze the water liquid from the pulp.  A press will do the trick.  I wouldn’t recommend doing this by hand, for if any liquid remains in the spirulina, it will effect the pH of the environment the spirulina is released into.
Once the spirulina algae has been de-liquified by pressing out the water, it can be cut up and stored in zip lock bags, in the freezer for up to 6 months. That’s it!  Now you can grow spirulina at home.  The only cost after your initial investment will be in purchasing more “PH UP!” and Distilled water.
Let me know about your growing experiences.
Spirulina Platensis
Spirulina Farm (Commercial grower in California)
Spirulina Farm (Commercial grower in California)
MIT Algae Photobioreator
How to make a Photo-Bio-Reactor
Thrown-together Algae Photobioreactor
Univeristy of Texas


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