Live FoodSaltwater

Growing a Phytoplankton Culture

Phytoplankton CultureBack in March of 2014, I decided I wanted to try my hands at a phytoplankton culture. There are many reasons saltwater hobbyists may want to start a phytoplankton culture, but first what is phytoplankton. Phytoplankton are essentially microscopic marine plants. Phytoplankton is a highly nutritional food that some corals and many small organisms like copepods eat. Some people will start a phytoplankton culture with the intention of dosing directly into their aquarium. Others will use phytoplankton to feed to rotifers and copepods, which is why I started my culture.

Many of you know that I have a mandarin dragonet named Bruce, and mandarins love to eat copepods. I wasn’t planning on culturing copepods though, because my mandarin eats pellets. I actually wanted to try to breed my mandarin and raise the fry, so I wanted to be culture phytoplankton to feed to other tiny organisms the fry would eat. But anyways, that’s not why you are reading this article, you want to know how to culture phytoplankton. Below are the easy steps I took to culture my own phytoplankton.


Supplies Needed

Since phytoplankton is one of the lowest things on the food chain, you need to make sure everything you use, like buckets, airline tubing etc. has never been used for your main display tank. There could be microscopic organisms or their eggs on the supplies without you knowing, which could destroy your culture by eating all the phytoplankton.


  1. 6500K Strip LightACFirst, I set up the area where I would be culturing the phytoplankton. This was in my basement which ranging from 55 to 65° F depending on the time of year. (I live in New England)
  2. Then I set up the lighting, I just used 2 strip lights I got at Home Depot with a 6500K color temperature.
  3. For containers I used a gallon jug from bottled water. I drilled a hole in the cap big enough for the airline tubing to fit through. I would also recommend drilling a second hole to allow air to escape, more on that later.
  4. Next you need to make the water for the phytoplankton and add it to the jug. I used mixed saltwater with a salinity of 1.019, and I also added 5mL of liquid fertilizer, miracle grow. I added the fertilizer to give nutrients for the phytoplankton to consume, based on recommendations from other hobbyists.
  5. Starting Phytoplankton CultureThe next step is adding your starter culture to the jug. If you want to grow a specific type of phytoplankton, I would recommend buying a culture online to ensure that only that phytoplankton is growing in your cultures. I wasn’t too concerned with the variety of phytoplankton, since I was just experimenting if I could successfully culture phytoplankton. I ended up using Phyto Feast and added enough to tint the water. I added more over the next couple of days as well.
  6. The last step is to put the rigid airline tubing through one of the pre-drilled holes and start the aerator. This helps circulate the phytoplankton to ensure it doesn’t all clump at the bottom. The rigid tubing can also be used as a stirrer every so often to help with clumping. The reason for the second hole is, once you start the aerator, without a second hole you pressurize the jug and either the top will pop off or one day you will lose power and not have a back siphon on your aerator and the water will shoot through the tube ruin your aerator and end up on the floor…not that I know anything about that. 🙂
  7. With the Phyto Feast, I noticed it took a little longer than what I had read other people reporting so just remember to be patient. Over time your water will turn green, and you can actually culture your phytoplankton. You can either split it into more bottles or feed it to something. Once your cultures are really producing, you will want to either split the culture or feed it off often, otherwise you run the risk of it becoming overpopulated and crashing.

There are obviously going to be different ways to culture phytoplankton; however the above method is what I used and it worked well for me. I’d love to hear from you in the comments section if you try this or another method of culturing your phytoplankton. What do you culture your phytoplankton for?


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