Culturing Phytoplankton

Live foods for your saltwater aquarium

Culturing phytoplankton

What is Phytoplankton?

Phytoplankton is a microscopic, free floating Plant cell that makes up the base of the Food Web. Their cells can not be seen with the naked eye but in areas of high cell counts they can turn the color of water into a dark green because of the Chlorophyll within the cells. Phytoplankton supplies Marine Life with great nutrients as well as clean the air we breathe.

Culturing phytoplankton

Phytoplankton is often used in saltwater aquariums and throughout the different stage of breeding of marine fish. The only drawback of  using live phytoplankton id the cost, whats why culturing phytoplankton is a great way to save money and provide an exceptional food source for your saltwater aquarium inhabitants.

Culturing Phytoplankton in the saltwater aquarium hobby Culturing phytoplankton is easy and can be a fun way to raise fresh foods for your critters that live in your saltwater aquarium. Weather your breeding marine fish or feeding your clams, culturing your own phytoplankton can save you a lot of money and it is very easy to do. If fact the hardest part of culturing phytoplankton is getting a good starter culture. Some people culture phytoplankton to use as food for culturing live rotifers.

Culturing Phytoplankton step by step video.


Culturing Phytoplankton Supply list:

  • Starter Culture of Phytoplankton
  • F2 or Phytoplankton Fertilizer
  • Syringe
  • Culture vessels (Clear water bottles)
  • Light fixture w/6500K Light bulbs
  • Aquarium Air Pump
  • Flex Air Line
  • Ridged Air Line
  • Gang Valve
  • Hydrometer
  • RO/DI Water
  • Synthetic Sea Salt
  • Rubbing Alcohol

Culturing phytoplankton step by step:

  • Sterilize the Culture Vessels with Rubbing Alcohol and set aside to air dry.
  • Drill holes in the caps of the Vessels with a 3/16 drill bit.
  • While waiting for the Vessels to dry pre mix the RO/DI water with Synthetic Sea Salt in a gallon jug until you reach 1.020 SG (Specific Gravity).
  • Once the Vessels are dry pour the Phytoplankton Culture into the vessel until they are 1/3 full. Than add the pre-mixed saltwater until the vessel is full.
  • Before adding the rigid airline and cap to the vessel add the Phytoplankton Fertilizer to the culture, measure it with the Syringe. 5ml per Liter.
  • Now Insert a rigid airline into the hole in the cap and cut to length. leave about 2 inches sticking out of the top and at the same time make sure the rigid airline touches the bottom of the vessel.
  • Using the flex airline and the gang valve, connect the vessels to the gang valve then to the air pump.
  • Then turn the air pump on and use the gang valve to control the amount of air flow going into vessels, adjust the air until it reaches a slow rolling boil.
  • If needed, use a Tac to make a small hole in the cap so the air can escape, if the air can not escape the air pressure will blow the cap off and will make a mess.
  • Set the vessels in front of  a 6500K (Kelvin) light, for 16-24 hours a day
  • The culture will grow darker and darker and in weeks time the cultures will be ready to spilt again using the steps above (Video Below).
  • Make sure to not wait to long to spilt the cultures or they will die off.
  • Phytoplankton can be stored in the refrigerator for up to a month. All it needs is a gently shacking ever other day to prevent the cells crushing one another.
  • Make sure to use new or sterilized Vessels every time the Phytoplankton Cultures are spilt because any amount of bacteria will kill the Culture.

For more information on culturing phytoplankton follow the link. If you have any question about culturing phytoplankton please feel free to email me at

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    • Steve, I don’t worry to much about matching the salinity when it comes to phytoplankton. If we were talking about rotifers that would be a different story.

      • So for rotifers would you culture them at your tank’s salinity or acclimate them after harvesting them from the 1.017sg?

        • With rotifers you are better off to build up the culture to the specific gravity (to match the aquarium you intend to feed) in their culturing vessel because they are very sensitive to fluctuations in specific gravity.

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