DIY Organic Iron Solution for Spirulina Cultivation

DIY Organic Iron Solution for Spirulina Cultivation

Last updated on June 8th, 2023

In organic spirulina culture medium, a DIY iron solution is used to replace chemical elements like ferrous sulfate acid and similar iron compounds. This iron rich mixture should be prepared 2 weeks in advance, prior to making the actual culture medium. If done properly, it will result in a reddish solution with the properties of iron(III) acetate.

Hint for the lazy readers: you can also buy Ferrous sulfate on Amazon.

Ingredients for making 1 liter of Organic Iron Solution

  • Large glass jar with a tight lid
  • Rusty nails or other rusty iron objects
  • White vinegar (acetic acid)
  • Juice from one lemon

how to make an organic iron solution for organic spirulina culture nutrients - iron(iii)

How to prepare the Iron Solution

Start by placing a handful of rusty nails in 1 L of vinegar and juice from one lemon.

Put all of those together in a glass jar and close the lid tightly.

Leave the solution sealed for 2 weeks, shaking the jar every other day for a few minutes.

As time goes by, the rust (Fe2O3?xH2OFeX2OX3?xHX2O) will react with the vinegar to form Iron (III) acetate, changing the color of the solution from transparent to deep red.

After 2 weeks, it is ready to use!

4 Responses

  1. Kyle Reply

    Hi Prathish , can you please give more details about making the solution ( i mean how many mL of this and that …).


  2. Prathish K Reply

    Thanks for the information. Do you have any idea for organic alternatives of urea, magnesium sulphate, phosphoric acid ?

  3. Michelle Scheeland Reply

    Thank you so much for this!!!!

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