February 14 2023


Microalgae Growth – Nutrients
algae pbr nutrients
PBR 1250L with ProLine nutrients part A and B on nutrient shelves.
Nutrients are the components of media that microalgae use to grow and build their cells. Nutrients stocks, or concentrates are mixed with water at precise concentrations to create “media”.  There are three general categories of nutrients that microalgae need: macronutrients, trace metals and vitamins.
Macronutrients – Nitrogen and Phosphorus

Macronutrients are those that are required in the greatest amount by phytoplankton.  The ratio between these nutrients is fairly consistent across microalgae and is known as the Redfield Ratio

Carbon is the most abundant element in phytoplankton, which we discussed in a previous Algae Growth Series article.  The next most abundant is nitrogen which is primarily used by phytoplankton to build proteins.  Phosphorus is the least abundant of these three macronutrients and is used mostly to build nucleic acids (DNA and RNA) as well as lipids (Finkel et al. 2015).  

Media recipes for culturing microalgae usually supply these nutrients in much higher quantities than would be expected in nature so that they are not limiting growth.


Most microalgae don’t require silicate to grow but for one group it is essential – the diatoms.  

Asterionellopsis glacialis, diatom
Asterionellopsis glacialis, a diatom with prominent silica spines.

Diatoms use silicon to build their cell walls and require it in similar proportions to nitrogen (Brzezinski 1985).  Silicate is added to microalgae culture media when growing diatoms, though most recipes do not follow a 1:1 ratio with nitrogen.

Limitation of these macronutrients is one of the easiest ways to get unreliable algae cultures. 

Trace Metals

Many metals are required at low concentrations for microalgae growth.  Most common recipes include iron, molybdenum, zinc, cobalt, and manganese.  Other metals may or may not be included depending on the recipe.  Trace metal solutions are often prepared with EDTA, which binds dissolved metals to keep them from precipitating out of the solution.

trave metals algae recipe
Trace metals included in different microalgae culture recipes. Recipes from Bigelow NCMA.



Just like humans, algae need vitamins they can’t produce themselves; however, unlike us, the vitamin requirements vary across microalgae lineages (Helliwell 2017). The three most common vitamins supplied in algal media are thiamine (B1), biotin, and cyanocobalamin (B12).

Media Recipes

There are a vast number of algae media recipes available.  Some considerations about which recipe to use are:

    • What strain of do you want to grow?
    • Does it have specific requirements?
    • What do other people growing this strain of algae use? Are their goals the same as yours? Do they use the same PBRs?
    • Are you preparing your media from natural seawater, or artificial seawater?  

If you are making salt water from reagent-grade salts it is a good idea to follow a recipe that is intended for artificial seawater.  These recipes will add more trace elements that would already be present if you were using a natural seawater base.


This is Part #5 of our Microalgae Growth Series.

Check out our other posts in the series that include: Light Intensity, Light Spectrum, Overview of Key Parameters and CO2 and pH.


Algae media recipes. (2020.). Retrieved April 19, 2021, from https://ncma.bigelow.org/algae-media-recipes

Brzezinski, M. A. (1985). The Si: C: N ratio of marine diatoms: interspecific variability and the effect of some environmental variables 1. Journal of Phycology, 21(3), 347-357.

Eighty years of Redfield. Nature Geosci 7, 849 (2014). https://doi.org/10.1038/ngeo2319

Finkel, Z. V., Follows, M. J., Liefer, J. D., Brown, C. M., Benner, I., & Irwin, A. J. (2016). Phylogenetic diversity in the macromolecular composition of microalgae. PLoS One, 11(5), e0155977.

Helliwell, K. E. (2017). The roles of B vitamins in phytoplankton nutrition: new perspectives and prospects. New Phytologist, 216(1), 62-68.