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How To Grow Your Own Phytoplankton

by Brian Dunleavy
How To Grow Your Own Phytoplankton

Are you looking for ways to improve your aquarium hobby skills? Did you know that many hobbyists save money by culturing their own live foods and phytoplankton in their homes?

Growing your own phytoplankton is extremely rewarding, and it is also one way you can heighten your aquaria knowledge and expertise. 


What Is Phytoplankton?

Phytoplankton are free-floating, tiny microscopic, photosynthetic, microalgae that form the bases of aquatic food webs, including inside your aquarium!

As mentioned, they are extremely small, so you will be unable to see them with the naked eye, as opposed to larger algae that are known to grow over your aquascape and tank's glass. Here is what they look like under a microscope:

Why Is Phytoplankton Important In Saltwater Aquariums?

Filter-feeding reef creatures including sponges, corals, small fish, and crustaceans will consume phytoplankton floating in the water column. 

Not only does phytoplankton provide a portion of natural food for filter-feeding animals, but dosing phytoplankton inside your aquarium also gives your tank inhabitants a nutritional boost. 

So, what exactly do you need to grow continuous supplies of phytoplankton?

Equipment For Growing Phytoplankton At Home

Culturing your own batch of phytoplankton is much easier than it sounds. It only requires a clean environment, water movement to provide oxygen in the water, light, some food, and a phytoplankton liquid starter culture. 

The majority of those things can be found at your local fish store (LFS) or online. 

To ensure you have everything to be successful, here are the items you will need to grow phytoplankton at home:

Once you have everything prepared, you can move on to the exciting part - growing the phytoplankton yourself!

7 Steps To Successfully Growing Phytoplankton At Home

As mentioned, growing your own phytoplankton at home is simple, and there are only a few steps to follow to culture your first batch. Let’s dive straight in!

Step 1: Set Up The Growing Vessel

This step is super simple! First, sterilize the phytoplankton container with boiled (hot) water or rubbing alcohol. This ensures that the container is clean and that nothing will interfere with your phytoplankton culture. 

Step 2: Organize The Lighting

After the phytoplankton container is sterilized, place the strip light above the container, or use a simple shop light. Even though any grow light spectrum or white light will work well, we recommend a 5W LED light for optimal phytoplankton growth. 

Step 3: Fill The Phytoplankton Container With Water

Next, fill the phytoplankton container with freshly mixed salt water. You mustn't use saltwater from your aquarium, as it may contain organisms like zooplankton that will eat your phytoplankton culture. 

Using freshly mixed salt water also reduces the chances of bacteria or other contaminants found inside your aquarium interfering with the phytoplankton's growth. 

Step 4: Adding Air To The Container

Now is the time to add air to grow the phytoplankton. A dual-output air pump is advised, as they tend to be stronger, providing your phytoplankton with enough oxygen to successfully grow. 

Apart from providing oxygen to the water, the air supply is important to keep the water flowing inside the container, so the phytoplankton cells are suspended and do not settle at the bottom. If phytoplankton settles at the bottom of the container, they usually crush each other, killing your culture. 

Plumbing Tips!

When you ‘plumb’ the air pump to the phytoplankton container, drill a small hole in the container lid, so that you can feed the air line through. We like to use a rigid acrylic tube connected to the top, so that the air is forced to stay at the bottom of the container. 

You can also use a suction cup to hold the tubing in place at the bottom of the phytoplankton container. 

One of the most important parts is to add a check valve and an adjustment valve to the air line. This prevents back-flow flooding and flow speed adjustments, similar to a human IV tube. 

What To Avoid?

While it may be tempting, you MUST NOT add an air stone. The small air bubbles produced by an air stone will act like a protein skimmer inside the phytoplankton container, skimming the phytoplankton culture and trapping them inside the bubbles. 

Step 5: Adding Fertilizer

Now it is time to add the phytoplankton fertilizer. As phytoplankton is an algae, it needs food to thrive and grow. 

As previously mentioned, we recommend Guillard’s F/2 Medium. To grow your phytoplankton at home with fertilizer, you should only need around 1.5 ml* of fertilizer per gallon of water. 

*Always check the dosage guidelines if using a different fertilizer.

Step 6: Add The Phytoplankton Starter Culture 

Now for the exciting part!

Add the phytoplankton starter culture into the container and give them time to grow.

Step 7: Splitting & Storing Phytoplankton

We suggest splitting your culture in half every 7 days. Store half into a storage container and place it inside a refrigerator to keep them alive. 

Every couple of days, give the storage container a gentle shake to prevent the cells from settling at the bottom. 


How Long Does It Take For Phytoplankton Culture To Grow?

Usually, phytoplankton culture will grow enough to fill 2 bottles, every 6-9 days. 

The amount of phytoplankton produced will depend on the light intensity, air bubbling, and the cleanliness of the environment. 

What If Growing Phytoplankton Is Not For Me?

If you have got this far, you feel that growing phytoplankton is not for you, but you still want to provide the best care for your aquarium, then you can supplement your aquarium with something like Phyto-Feast Concentrate or Phyto Feast Live


So there you have it, it really is that simple to grow phytoplankton in your home! As phytoplankton is a simple algae, you only need to provide a starter culture, light, some nutrients (food), oxygen, and a clean environment. 

Growing your own batch of phytoplankton provides many benefits for your aquarium, plus it is extremely rewarding!

If you have any questions regarding growing phytoplankton, or what phytoplankton supplements we have to offer, do not hesitate to contact the Reefco Team, we are always happy to help with any aspect of your aquarium setup

by Brian Dunleavy