DIY Organic Iron Solution for Spirulina Cultivation

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 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!