The culture medium – or the water in which spirulina grows – is one of the most import parameter when growing spirulina at home. Why? Because spirulina will absorb whatever is in its environment, which is, you guested it, the culture medium.

This means that spirulina will “bind” with heavy metals and other toxins that you have in your body but spirulina will do just the exact same in the environment where it grows.

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Therefore, if you grow spirulina in water which contains heavy metals it will “absorb” them and accumulate them. And that’s no good! That’s not something you want to eat! And that’s true not only for heavy metals but also for radiations!

To expand on this point, did you know that a spirulina farm has been built in Chernobyl to help reduce environmental radioactive radiations in the area? Not only that, but spirulina is also given to Chernobyl’s children (not the one that is grown on site of course) and Mr. Belookya, Chairman of the Byelorussian Committee of “Children of Chernobyl”, reported that children fed spirulina for 45 days showed a 83% diminution of radioactivity in the urine (83%!!) and an increase in t-cell suppressors!
For the same reason, I would advise to steer clear from spirulina made in China. Just because the environmental standards are not the same over there and because China’s air is on average very polluted (not everywhere of course).

So, where to start?

1. The Water

The water need to be pure for the reasons we just explained. This doesn’t mean that you have to use bottle water but you should filter the tap water – something like a Brita filter will do just fine.

If you use river water,  use UV filters in addition to active carbon filter(the Brita type), as you might have other algae or organisms in the water that could compete or eat spirulina. One of the most frequent algae one can find is Chlorella or Navicula. These algae can cause problems mainly at the start of the culture, when spirulina are not dense enough to stop light penetration deeper in the tank.

Once the spirulina culture is dense and thriving, there are very little risks of contamination, mainly due to the growing conditions, very specific to spirulina. If the culture has a pH over 9.6 and a Secchi lower than 3, the risk are minimum. (I would not recommend harvesting if you do not meet these basic conditions, more on that here).

It is interesting to note that even though spirulina needs water to grow, a culture will need up to 30 times less water (30!!) to produce one pound of spirulina protein compared to the traditional production of one pound of beef protein (Fig. 1)! You’ll need water to fill up your tank only once and then add just enough to make up for evaporation. That’s it! Spirulina is truly an environmentally friendly culture!

Gallon of Water Used to Produce one Pound of Protein


2. The Nutrients

Just like a plant spirulina needs an variety of nutrients to thrive in your tank at home.

Spirulina basic needs are:

  • An alkaline water
  • A source of fixed nitrogen
  • A source of iron, phosphorus potassium and sulfur.
  • A source of carbon (this can be the CO2 atmospheric)
  • A source of trace calcium, chlorine and magnesium.

Different culture media can be found in the literature, the Zarrouk medium, the Jourdan medium, the CFTRI mix, the BG-11 medium, etc.

I found the Zarrouk medium be very effective and spurred a very good growth rate of spirulina. All the ingredients for this medium can be bought on line (hint, hint, we’ll have a shop ready for you soon so come back regularly to check it out 🙂 ). You can also buy larger quantity that will last for almost a year and reduce even more the cost of production.

Here is the composition of the Zarrouk Medium, that I recommend to use for your tank at home:


Quantity per liter of water

NAHCO3 (Sodium bicarbonate)


K2HPO4 (Dipotassium hydrogen phosphate)


NaNO3 (Sodium nitrate)


K2SO4 (Potassium Sulfate)


MgSO4 . 7 H2O (Magnesium sulfate)


CaCl2 (calcium chloride)


FeSO4 . 7 H2O (Ferrous sulfate)


EDTA (ethylene diamino tetracetic acid)


Solution A

1 ml

Solution B

1 ml

To make Solution A, you’ll need:

Solution A

Quantity per liter of water

H3BO3 (Boric acid)


MnCl2 . 4 H2O


ZnSO4 (Zinc sulfate)


CuSO4 (Copper Sulfate)


MoO3 (Molybdenum oxide)



To make solution B, you’ll need:

Solution B

Quantity per liter of water

NH4VO3 (ammonium vanadianate)


K2Cr (SO4)4 . 24 H2O (Chrome alun)

960 . 10 -4g

NiSO4 . 7 H2O (Nickel sulfate)

478. 10 -4g

Na2WO4 (Sodium wolframate)

179. 10 -4g

Co(NO3)2 . 7 H2O (cobalte nitrate)

44. 10 -4g

Okay, I know… All these nutrients might seem a little bit daunting. Especially if you don’t like chemistry. But it’s actually pretty simple. It’s just like following a recipe. Just take one nutrient at the time and add them one by one, and once you are at the bottom of the list; you’re done 🙂

If you still think that this is like too much chemistry (and I can understand…) hang in there, soon we’ll be offering ready mix culture medium!


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