Growing Phytoplankton

This article was originally published in Garden Culture Magazine US02.

Yes, this article is about cultivating that ‘green stuff that grows in the water’. Actually, phytoplankton can be almost any color. At the moment, you’re probably wondering why would anyone want to grow watery goo? The best reason for growing phytoplankton is, of course, because you can. It’s an amazingly fast and simple process that’s fun to watch, but there are some things this goo can be used for.

There are thousands of different species of phytoplankton, but what is it ? Plankton is a general name for all organisms that inhabit water and simply float around. This means, they go wherever the current takes them. These can be anything from animals to bacteria, but in the case of ‘Phytoplankton’ – we are talking about plants. Microscopic plants. Although their tiny cells can grow to great numbers making the waters they live in heavily colored.


In nature, phytoplankton is on the bottom of the food chain. Like any other plant species, phytoplankton consume sunlight and minerals from water. In turn, phytoplankton is consumed by larger organisms living in the water. The first people who began growing their own phytoplankton were aquarium owners. It’s a great benefit to be able to control the whole food chain. This is especially important when dealing with ecological systems with a high density of living organisms in a small space where a lot of metabolism is happening.

From a medical perspective phytoplankton is also interesting, specifically marine phytoplankton that grows in the oceans. Salt water is quite dense in minerals that are vital for life. Phytoplankton very efficiently concentrate these minerals and incorporate them into their
cells. It can then be dried and turned into a powder containing a range of essential minerals in nearly ideal ratios for human consumption.

Huge benefits are claimed to come from taking phytoplankton supplements. Many problems and diseases are said to be cured – according to specialists on the internet. No one knows how many of these claims are true. Considering the wide range of minerals and other nutrients,
they could be onto something here.


First, identify and find a specimen of the species of beneficial goo you want to grow. Maybe you’ll find it in a sample of water from a local creek with tools you used in high school biology. You can also order a scientifically prepared culture online. A number of places will happily sell you a tube of the exact species requested.

Specimen in hand, you have to find out the condition this species likes, the tolerable pH level along with its required nutrient density (Electric Conductivity, PPM). Next make a solution to meet these needs using basic plant nutrients. Make sure to use nutrients with a wide variety of micronutrients, or you’ll fail to create a mineral dense supplement. Marine phytoplankton require marine conditions. Special salt mixtures are available to mimic their native ocean realm.

You can grow phytoplankton in almost any translucent container, glass is probably best. Now you need to introduce carbon dioxide. Like all other plants they consume carbon dioxide, which is easily introduced using an aquarium air pump. These bubble carbon dioxide sufficient air into the water regularly for your crop of goo.

Be patient. It will take some time before anything really happens. Growth of these tiny plants is exponential. A moment will come when the color of the water starts to change. The color of the water changes according to the pigments that are contained in the cells.


You must have light, but the color of the light depends on the type of phytoplankton you’re growing. The amount of light depends on the amount of culture, however with air bubbles agitating the solution, all the cells’ light distribution is better than in most other agricultural systems. Fluorescent lights seem to perfectly suit phytoplankton, but it may well be that Plasma or LED lighting is even better. These are still unknowns since growing phytoplankton isn’t ‘mainstream’ yet.

Once the density of phytoplankton is high enough, you can harvest. Separating the phytoplankton from your solution is done with a sieve, and may require ultra fine sieves. Depending on the planned use, the material can either be used fresh, or dried and turned into a powder. Be advised! There can always be harmful microorganisms when consuming raw products.

So, you have dried your phytoplankton harvest. What to do with this powder? It may enhance soil life, by increasing the availability of micronutrients and add proteins and phytohormones that are the same hormones found in plants on land. It can also be used in aquariums, or to brew compost tea.

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