How to Culture Nannochloropsis (Nanno) Phytoplankton
Phytoplankton is the foundation of every live food chain in reef tanks. It feeds copepods, rotifers, clams, corals, and filter feeders - and culturing your own is cheap, simple, and sustainable.
For beginners, such as people starting their first culture, nannochloropsis is a hardy and easy strain to start with.
What You’ll Need
Super clean, sterilised culture container (5–20L is common, cylindrical, rectangular, hexagon doesn’t matter, something that holds a decent amount of water is all you’re after)
RODI saltwater (1.018–1.023 salinity)
A bottle of healthy live phytoplankton which you can obtain here.
Fertiliser which you can also obtain here.
Light source (6500K or grow light)
Gentle aeration (rigid tube + airline tubing)
Finally patience, not all cultures will succeed, it’s wise to keep 100-200ml in the fridge so that you can use it to recover from crashes.
Steps
1. Fill your container
Use clean saltwater. Add your fertiliser as directed.
2. Add phytoplankton
Pour in your starter culture.
3. Aerate & light it up
Use continuous aeration to keep cells suspended. Light it 16–24 hours/day. A cheap LED or sunlight works fine.
4. Wait & watch
Over 5–7 days, the water will darken. That’s your phytoplankton multiplying. Avoid overgrowth as this can causes cell shading, nutrient depletion and cell lysis(death).
5. Harvest & feed
Once it reaches a rich green, pour off what you need through a sieve if feeding pods. Clean your culture container and repeat the cycle.
6. Maintain or split
Split cultures weekly to avoid crashes.
Tips
Phytoplankton requires significant movement, ensure there is enough to agitate the surface significantly.
Use different strains for broader nutrition
Always clean your culture container(s) between harvests and never top up an existing culture.
