BLOG# 2 -Edible Algae System - (Growing Spirulina in space)

System Concepts

Updated version 1.3

This is my 2nd blog post in a series of blog post for the Design Challenge 1 Meter of Pi



Blog# 1 EAS - Steps to Growing Spirulina Algae

Blog# 3 EAS - Research Instrumentation



The system is designed to automate the successful production of Edible Spirulina.

To grow any Algae, there are several product cycles involved in getting a good product:

  • Getting the right Materials
  • Preparing a Solution Mix with the Spirulina living Culture
  • Growing Cycle
  • Backup Culture
  • Product Harvesting


In this blog, I will describe how i plan to manage the growing cycle of spirulina algae. The primary components of growing spirulina successfully are: Water, Temperature, ,Co2 and Light. In my design, I will use automation to control the growing cycle. The Growing Environment will be monitored by Controller modules that will support ideal growing conditions for the Spirulina.


The other cycles could possibly be automated as well, but I leave that to a future design enhancement.


Growing Housing Unit (GH)


As I mentioned, to grow Spirulina Algae successfully,  an ideal environment of Water, Temperature ,CO2 and Light must be monitored and maintained during the growing process. To accomplish this, a Growing Housing (GH) will contain a growing environment unit (GEU) and up to 2 Controller Units (CU) to maintain Water, Temperature,,CO2,PH and Light Exposure of both the GH and the GEU environment.


Here is the component breakdown within the Growing House

  • Growing Housing Unit GH
    • This is the housing that contains a:
      • spirulina growing tank
      • instruments to aid in the growing process
      • Raspberry PI controller to control these instruments.
        • Growing Environmental (GEU)

          • This is the environment the contains the growing Spirulina in a tank of water.
          • attached to the growing tank are the following Instruments:
            • A light Source outside the water of the tank
            • A Heater in the water of the tank.
            • A Pump outside the tank that pumps air down a flexible hose, that is placed in the water for aeration.
            • A Water Temperature Probe to monitor the temperature of the water.
        • Controller Unit  Raspberry PI

          • PM487 Automation Hat
            • This controller will control the instruments used on the GEU.
            • It will be programed to manage and monitor the instruments attached to the GEU
          • PM486 Enviro Hat
            • This controller will control the instruments used to maintained and manage the environment within the GH
            • It will be programed to manage and monitor instruments in the GH.


  • The following diagram describes this relationship.
  • The Growing Housing Unit will be one quarter of the space of 1m Cubed required by the Design Challenge.


Growing Environmental Unit -- GEU --- What's Inside.




Controller Unit (CU)


GEU instruments controlled by the CU

  • Temperature of the water
    • between 8C (46.4F) AND  45C (113F)
    • studies have found that the ideal temperature is 35C (95F)
  • Oxidization in the water (Mixing)
    • Turn On the  AIR Pump
    • 1 minute 3 times a day
  • Amount of light exposure
    • Studies show to improve the growth rate:
    • a light can be turned ON every hour for 45 minutes and OFF fo r15 minutes
    • From 7am to 10pm
  • Alerts
    • send out alerts if certain components of the GEU  are out of operation range, malfunctioning, etc.
    • Send the alert in an email to the system operator.
    • Example: The temperature of the water is out of range.
      • Others?
  • Monitoring
    • Real time.
      • Send telemetry data to a database. for analysis
    • Intelligent rules programed to respond to an action with one of the components.
      • For example, If the temperature of the water is below or above a certain temperature turn on the heater and the pump



GH instruments controlled by the Automation HAT

  • Water Pump Switch
  • Light Switch
  • Heater Switch

GH Environment elements controlled by the  Enviro HAT

  • Humidity
  • Temperature
  • Check Room Light


4 Growing Housings = 1 Meter Cubed space

  • There will be 4 growing housing units a quarter of a cubic meter in volume
  • With four GH units with 20 gallon tanks in each one, that will equal a total of 80 gallons of water in the system.
  • The GH units can be stacked as described below or positioned side by side.
  • The combination of these quarter cubes will make up the cubic meter required by the challenge.


Spirulina yield

  • Spirulina can roughly be harvested ever 2 weeks
  • it Will lass for 2 days  under refrigeration.
  • It can be frozen in ice cube tray to allow it to keep longer.
  • The yield formula is:
    • 7Liters (1.8492 gallons) = ~ 1 tablespoon of fresh Spirulina
  • the yield for 20 gallons equals 36.984 tablespoons
    • Then a system with 80 gallons of water can yield 147.936 tablespoons or 9.246 Cups of Spirulina
  • This amount of Spirulina can be used to sustain human life on a long journey or give nutrition to malnourished children.

Conclusion and summary

  • This blog has explained the system concepts and outlined the system design on growing Spurling Algae.
  • It has described how I have included the supplied components in the challenger kit
    • Raspberry PI

    • Automation Hat
    • Environ Hat
  • The next Blog will include my research on Instrumentation needed to aid in the growing of Spirulina in the Growing Housing. GH Unit



Blog# 1 EAS - Steps to Growing Spirulina Algae

Blog# 3 EAS - Research Instrumentation