Growing Algae

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Author: Marc Rosner

How would you like to be a chemist, optician, taxonomist, histologist, geneticist, and hydroponicist all at once? You can if you grow algae. The science of growing these fascinating aquatic, plantlike organisms overlaps with many fields. Algae range in size from microscopic single cells to kelps (seaweed) nearly as tall as an oak tree. Some algal species can live in boiling natural springs; others thrive in the polar wastes; still others are found at great ocean depths at the heated openings of geothermal (heat energy supplied by Earth) vents.

Chemistry is the study of the nature of matter. Optics is the study of light. Taxonomy is the systematic classification of organisms. Histology is the study of tissue structure in organisms. Genetics is the study of inheritance of traits (features of an organism, such as hair color). Hydroponics is the method of growing life forms in nutrient broths.


  • metric measuring spoons and cup
  • plant fertilizer (e.g., Mirade-Gro)
  • saucepan
  • stove or hot plate (requires adult help)
  • narrow glass jar
  • dropper bottles
  • butter knife
  • film canisters or other small containers
  • notebook and pencil
  • Petri dishes or jar lids
  • microscope or magnifying glass
  • paper


Algal blooms have occurred in many bodies of water due to fertilizer runoff from farms and lawns. The excessive growth of algae leads to eutrophication, a reduction of the oxygen supply. This is followed by the death of fish and other water-dwelling creatures, causing severe harm to the aquatic ecology.

Growing Algae

Growing Algae

Each year, we can grow 14.7 tons of algae per hectare used for algae cultivation. Why would anyone want to grow algae? This industry has many potential uses, from producing materials for the pharmaceutical industry to designing oil-eating algae to help clean up tanker spills.
The leaflike parts of many algae consist of only two layers of cells coated with a clear substance. When the algae dry on paper, they seem to have no thickness and look like lines drawn with ink in exotic colors.
  1. Start the preparation of your nutrient broth by mixing 5 mL of plant fertilizer with 500 mL of tap water in a saucepan.
  2. Ask an adult to boil your broth on high heat for about 10 minutes or until it boils down to 250 mL, whichever happens first. Allow the broth to cool for 10 minutes.
  3. Transfer the liquid carefully to a l-L glass jar that has been washed in warm, soapy water, rinsed, and dried.
  4. Collect algae-rich water from a local source. Be sure your collection equipment and containers are sterilized by washing them in soapy water and thoroughly drying them or running them through the dishwasher. That way you will be less likely to contaminate your samples. The best place to find algae is in a small cove in a pond with green, scummy, stagnant water. Slow-moving streams work, too. You can collect water samples from the surface using a dropper bottle for each sample You can scrape green algae from a rock using a butter knife and transfer the sample to a film canister or other small container. You can also collect algae directly from the soil, scooping a sample into a film canister. Keep your samples wet or moist in their containers, at an even temperature. The faster you transport them, the better. Make sure to keep notes on where each sample originated.
  5. Add a small specimen of each sample to a Petri dish filled with the nutrient broth you made in steps 1 to 3. (If you can't get Petri dishes, use jar lids that have been through the dishwater on a hot cycle. Use them right after they come out and have cooled down.)
  6. Allow your specimens to bloom (become densely populated with microorganisms) over several days. Try to store the specimens in a location with temperature and light conditions similar to those where you collected the original samples.
  7. Using a microscope or a magnifying glass, you may be able to sort the algae by type with a clean dropper. Try to find one or a few growths that are identical, and carefully transfer them to a new, clean nutrient-broth dish. Allow this algae sample to bloom. This should be a "pure" sample of one alga type.
  8. You can transfer algae to a sheet of paper and let them dry. Then mark the paper with the date, time, and place you found the sample.
  9. You can perform experiments on algae to see how well different types grow under different conditions, varying the fertilizer type, light source, or temperature.


Pond Water Zoo: An Introduction to Microscopic Life by Peter Loewer and Jean Jenkins (New York: Athenuem, 1996).

Ponds and Pond Life (Nature Detective series) by Anita Ganeri (Danbury, Conn.: Franklin Watts, 1993).

Microbe Zoo:

The Pleasures of Pond Scum:

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