UTEX sells 5% F/2 Medium at 1X concentration only. Stock solutions and individual components for this specific medium are currently not available for purchase.

5% F/2 Medium

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5% F/2 Medium

For marine algae that require salinities at 48 ppt.


For 1 L Total

  1. Dissolve 15 g of natural sea-salt in approximately 900 mL of non-pasteurized seawater (30-35 ppt).
  2. Add each of the components in the order specified (except vitamins) while stirring continuously.
  3. Bring total volume to 1 L with non-pasturized seawater.
    • For 1.5% (w/v) agar medium add 15 g of agar into the flask; do not mix.
  4. Cover and autoclave medium.
  5. Store at refrigerator temperature.

# Component Amount Stock Solution Concentration Final Concentration
1 Seawater
1 L
2 Natural sea-salt 15 g/L
3 NaNO3
(Fisher BP360-500)
1 mL 7.5 g/100 mL dH20 880 µM
4 NaH2PO4H2O
(MCIB 742)
1 mL 0.5 g/100 mL dH20 36 µM
5 Na2SiO39H2O
(Sigma 307815)
1 mL 2 g/100 mL dH20 70 µM
6 Trace Metals Solution 1 mL/L
7 Vitamin B12 1 mL/L
8 Biotin Vitamin Solution 1 mL/L
9 Thiamine Vitamin Solution 1 mL/L

Important Notes To Consider:

  • The quality of water, including natural seawater, is important. The term 'dH2O' generally refers to distilled, deionized, distilled/deionized water, Milli-Q water (Millipore Corp.), etc. Natural seawater and natural freshwater should be obtained from a non-polluted source.
  • When dissolving chemicals, wait for the first component to dissolve before adding the second. Stirring, and sometimes the addition of heat, is often required to dissolve the chemicals efficiently. Preparation of stock solutions for frequently made algal culture media make preparing media convenient but also necessary to avoid errors from weighing very tiny amounts.
  • Attention should be given to the pH of the final medium. In most cases, if pH adjustment is required, this occurs before sterilization. Please note that autoclaving removes carbon dioxide from media lacking carbonate stabilizing buffers. This would make the medium very alkaline soon after removal from the autoclave. In these cases, you should wait approximately 24 hours for gaseous equilibrium before inoculating the medium.