Spirulina is a type of blue-green algae that’s loaded with nutrition: protein, antioxidants, and numerous vitamins and minerals. It is a simple organism that grows easily in warm water. However, because algae can absorb toxins found in the environment, some people opt to grow their own spirulina at home in safe and controlled conditions. Others simply prefer the taste and texture of fresh spirulina. Once you have a few supplies set up, your spirulina colony will pretty much take care of itself.

Get a tank. Most home growers find that a standard size aquarium is perfectly adequate as a space to grow spirulina in. A tank that size will supply a family of four with plenty of spirulina.

Gather harvesting equipment. A spirulina colony can appear thick, but it’s mostly water. Once it’s ready to eat or use, you’ll want to squeeze out the excess water. For most home growers who will want to use only a small amount of fresh spirulina at a time, a fine cloth or mesh will work just fine. In addition, you'll need a scoop to get the spirulina out of the tank

Purchase minerals to encourage algal growth. Trying to grow spirulina in plain water won’t necessarily lead to great results. To have an optimal colony, you’ll need to add specific minerals. You don’t have to be an expert, though--you can buy premixed mineral “food” for spirulina from health and organic stores as well as online.

Buy a spirulina culture. To get your own spirulina colony going, you’ll need a bit of live spirulina as a starter. Check with your local or favorite online health food or organic supplies store and ask for a spirulina starter kit.

Position your tank in a warm, bright place. If possible, set your tank so that it is near a south-facing window that gets lots of sunshine. Spirulina algae need plenty of light and warmth to grow well.

Prepare your medium. Spirulina growers refer to the “medium” the algae grows in, but this really just means the water in the tank, with the mineral “food” added. Fill your tank with filtered water, and add the mineral mix according to the package instructions.

Check the temperature of the medium. Ideally, the temperature in your tank should be around 35°C (95 F), but above 38°C (100.4 F) is too warm. Use an aquarium thermometer to make sure your tank will provide the right temperature for your spirulina.

Add the spirulina starter. You should follow the exact instructions that come with your bottle of spirulina starter to be sure, but usually it’s simple to add the starter culture. Generally, you just pour one half to three-fourths of the bottle into the medium in your tank.

Watch your spirulina colony grow. At first, your spirulina colony will seem thin, but over time it will thicken and expand in size. Most of the time, you won’t have to do anything to your colony other than let it grow.

Agitate the tank occasionally. Your spirulina will need oxygen to thrive. Some growers will use an aquarium pump to ensure a supply of oxygen, but this isn’t strictly necessary. To help air get into the water of your tank, you can simply stir the medium occasionally.

Harvest your spirulina after about 3-6 weeks. Once your spirulina is thriving, you can start taking some out to consume. All you have to do is scoop some out! Most people find that about a spoonful of spirulina at a time is enough if you are consuming it fresh.

Filter your spirulina through a fine cloth. Place the spirulina you took from your tank onto the cloth. Hold it over a sink or bowl and gently squeeze out the excess water. You’ll be left with a thick green paste. Use this fresh spirulina in smoothies, top your favorite foods with it, or enjoy it all by itself.