Phytoplankton Culture

Phytoplankton Culture: A Guide to Growing Phytoplankton at Home

In the ocean, fish and invertebrates have access to nature’s bounty, and they dine at one of the best buffet lines ever created. In the home aquarium, however, food tends to be much less interesting. One thing you can do to liven up the food chain in your aquarium is to culture phytoplankton at home. Phytoplankton are one of the basic building blocks in the food chain–and can be fed to coral, claims, or used as a nutrition-packed food for other live foods like rotifers or brine shrimp. If you are interested in breeding saltwater fish, you will need to master the art of phytoplankton culture–so that you can feed the tiny fry that are born.

I will share with you my method for phytoplankton culture, including a list of the equipment you need.

The first decision you need to make before even setting up your phytoplankton culture is–what species do I want to culture? This article doesn’t go in depth about the relative merits of the various types of phytoplankton culture–but you can find that information here.

Here is a list of the equipment you will need to start a phytoplankton culture, such as Nannochloropsis occulata, at home

Phytoplankton Culture: Equipment List

  • 48″ Shop light
  • 2 x 48″, 40 Watt fluorescent bulbs
  • On/off Timer
  • Air pump
  • ~10 ft. Flexible airline tubing
  • ~ 3 ft. Rigid airline tubing
  • Multi-outlet airline splitter/valve
  • 3-4 x 1 Gallon water jugs
  • Aquarium salt
  • Fertilizer f/2 Formula
  • Phytoplankton starter culture, like Nannochloropsis occulata

You could get most of this equipment by shopping at your local hardware and pet stores or online at If you purchase anything by using that link, I will receive a small commission at no direct cost to you. No pressure to use it.

You can get phytoplankton cultures and fertilizer from a specialty vendor, Florida Aqua Farms.

How to set up your phytoplankton culture equipment

  • Mount the fluorescent light horizontally on a wall about table-height
  • Slide the table up against the wall, just under the light
  • Spread your culture bottles out to maximize surface area exposed to the light
  • Cut 3 lengths of 12 inch rigid tubing and 4 lengths of flexible tubing, 3 long enough to reach from the bottles to the splitter and 1 long enough to run from the air pump to the splitter
  • Attach flexible tubing to splitter, pump and rigid tubing
  • Insert rigid tubing into culture bottle
  • Turn on air pump
  • Fill bottles with a small amount of freshwater to test and make sure all 3 airlines create a modest flow of bubbles. Adjust flow rate on splitter as necessary to create uniform moderate flow

This is what my set-up looks like:

Phytoplankton Culture Set-up

Phytoplankton Culture Set-up

Making the  Phytoplankton Culture Media

Make a fresh gallon of saltwater with a specific gravity of 1.014.  Stir the water, then add the fertilizer according to the label–if using Micro Algae Grow, then add 40 drops per gallon. Let the water ‘age’ over night before using.

Establishing the Phytoplankton Culture

Add enough media to the culture to double the volume.  Insert a rigid airline and start a moderate flow of bubbles.  Watch the culture over the next few days.  Diluting the culture should make it lighter in color–when the culture returns to the original color, or darker, dilute again by 50% and repeat until the culture volume reaches 1 gallon.  Another popular culturing volume is 2L–you can use clear soda bottles to do that.  The main point here is to take it slow in the beginning, allow your culture to take-hold and help keep possible contamination at bay.  Once your culture has reached a deep green color in the 1 gallon vessel, you are ready to subdivide.

Grow-out and Harvest

Once the culture is up and running, you will want to establish a separate culture in a few different bottles.  Pour 1/3 of the culture into each of 2 new bottles, so that there is 1/3 in all three.  Fill them back up with fresh media, set them in front of the light and get ready to harvest in a week.  From then on out, harvest 2/3 of each bottle, keep the remaining 1/3 in the original bottle and top-off with new media.  Put the airline back in and you’re culturing like a pro.

Phytoplankton Culture Storage

Use the phytoplankton immediately or store it in the refrigerator until it is needed.  If storing the phytoplankton for longer periods of time, you’ll notice that the phytoplankton cells settle to the bottom–make sure you shake it up at least once a week or the culture will spoil/rot.

Dosing Phytoplankton

Here is more information about how to dose phytoplankton in your reef tank

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Written by Albert B. Ulrich III. Follow me on  and Twitter

Albert B Ulrich IIIPhytoplankton Culture