Saturday, July 11, 2015

Low-tech Spirulina Cultivation

Method


Spirulina is quite hardy and is fairly easy to produce.  That being said, it's important to prevent drastic changes in the environment in order to maximize productive efficiency.   We start with a small culture, and place it in a 2 Liter bottle of culturing media with an aquarium bubbler, set on a regular timer, in a moderately sunny window.

Since we do not know the levels of pH and salinity originally used in our new culture, we add a few drops of our media to the culture, slowly acclimatizing it.

Culturing Media


This is a recipe for culturing media, adapted from several sources, using the cheapest, simplest ingredients available:

Starter Media (2 L):

  • Sodium Carbonate (soda ash) - 2 tsp - Products sold for use in pools often contain additional compounds.  Stick with lab or technical grade.  The arm and hammer laundry soda seems to be ok.
  • Sea Salt (NaCl) - .5 tsp - Provides micronutrients and sodium.
  • Compost tea (2 L) - Properly filtered, this provides soluble minerals
  • Baking Soda - 1/2 tsp - Adjusts pH
  • Potassium Nitrate - 1/2 tsp - Provides extra Nitrogen in order to increase density potential. 
It is important to have sufficient sodium, carbon, nitrogen, potassium and phosphorous.  Additionally, micronutrients such as iron, calcium and magnesium are important elements for the algae's growth.  We have had success using mineral rock powder for micronutrients without clouding the media excessively.

Replacement Media:


As you harvest, you will need to replace minerals taken out by the spirulina.  I am currently working on a suitable non-sterlizing fertilizer blend.  There aren't many vendors in this area who deal in the various fertilizers that are available.

Other Notes


Do not use Miracle-gro, or any other fertilizer that contains muriate of potash as a potassium source.  In liquid, this element breaks down to potassium and chlorine, which will sterilize your colony, just as it sterilizes soil. 

Urea is a decent protein source in moderation, but it can overload your culture, so be careful.

References:


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