Dosing Phytoplankton

When I first started my reef aquarium I was clueless to dosing phytoplankton and the benefits of dosing phytoplankton in my reef tank.

Over the years as I gained experience in the reef aquarium hobby I learned about various aspects of nutrition in the reef aquarium. It is my opinion that the best source of nutrition and amino acids is by dosing phytoplankton.

In this article, I will share with you what is phytoplankton as well as outline the importance of phytoplankton in a reef aquarium. I will also show you a very helpful phytoplankton dosing schedule.

Phytoplankton Definition

Phytoplankton is photosynthetic algae that consist of microscopic plants. It is the most vital plant substance in the entire universe and grows to feed off nutrients in the water as well as energy from the sun.

How To Dose Phytoplankton

I personally dose 5ml of phytoplankton per 10 gallons of water every few days. It is important to start small and work your way up so I recommend following the below table for recommended dosing. If you dose too much your tank will likely suffer issues as result.

WeekPhytoplankton Dosing Amount
Week 11ml every 3 days
Week 22ml every 3 days
Week 33ml every 3 days
Week 45ml every 3 days
Week 55ml everyday
Phytoplankton Dosing Schedule

Dosing phytoplankton is actually really easy. Best of all it is also easily grown in your closet which will provide an almost endless supply of phytoplankton. You can culture your own phytoplankton using this phytoplankton culture tutorial.

Why Dose Phytoplankton

  • Feeding – Filter feeders such as coral, copepods, zooplankton eat this to keep healthy. When I first started dosing phytoplankton I noticed my coral were much happier and showing exceptional health and growth as well as coloration.
  • Fishless System – If you want to grow coral and have no fish, this is a great option for feeding your coral.
  • Nutrients – Reef tanks require some levels of nutrients that feed your coral. Nitrates and Phosphates should have some presence in your reef tank. This will increase the nutrients in your reef tank.

Harvesting Phytoplankton

Phytoplankton typically takes about 7 days to fully grow to a density that is perfect for dosing in your reef tank or to dose into your copepod or rotifer cultures. After 7 days it is ready to split into two or three separate cultures.

You can keep splitting the culture every 7 days to ensure that you have an ample amount of phytoplankton for dosing and other needs.

Here is a picture above my own personal 200 gallon reef aquarium displaying my harvested phytoplankton.

 Dosing Phytoplankton in Saltwater Aquarium - Reef Tank. 10 newly cultured Nannochloropsis after 1 week of production.
Nannochloropsis Phytoplankton Newly Cultured/Harvested

Best Phytoplankton for Reef Aquariums

Personally, I like Nannochloropsis Phytoplankton because it is an energy-rich food with high levels of polyunsaturated fatty acids for my fish and larvae. When I am breeding fish this is important.

Another great thing about Nannochloropsis is that it is also very easy to produce. It is the phytoplankton that always does well for me and rarely has a crash.

If you want to purchase some phytoplankton for your reef tank I recommend checking out this Amazon listing here for a live culture of phytoplankton. This kit includes the needed live phytoplankton and a culture vessel which will allow you to increase your stock. Doing this will allow you to never have to purchase another bottle of phytoplankton.

If you want to just purchase your bottles for dosing you can do so here.

Here is another great product but you will not be able to culture this one by AlgaeBarn. If you have luck culturing this then please reach out to me as I have tried to and it always crashes and never does anything for me. This is a great product to dose it you prefer not to culture your own phytoplankton.

Why Are Phytoplankton Important

Phytoplankton is small microscopic algae that feed zooplankton and other small organisms. Phytoplankton is at the very bottom of the food chain hence its importance for newly created marine life.

These free-floating eggs and larvae require phytoplankton to survive and grow. This is why it is so important for new marine life. It is filled with high amounts of fatty acids and nutrients.


I really hope this content has been helpful. Feel free to leave a comment below with any questions you may have. Do you dose phytoplankton or culture it? Leave a comment with your experience.

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