UTEX sells Waris Medium at 1X concentration only. Stock solutions and individual components for this specific medium are currently not available for purchase.

Waris Medium

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Waris Medium

Modification of the original recipe. Suitable for xenic cultures of some desmids.


For 1 L Total
  1. To approximately 900 mL of dH2O, add each of the components in the order specified while stirring continuously.
  2. Adjust the pH to 6.0.
  3. Bring the total volume to 1 L with dH2O.
  4. Cover and autoclave medium.

# Component Amount Stock Solution Concentration Final Concentration
1 KNO3
(Baker 3190)
1 mL/L 10 g/100 mL dH2O 0.99 mM
2 MgSO47H2O
(Sigma 230391)
1 mL/L 2 g/100 mL dH2O 0.081 mM
3 (NH4)2HPO4
(Fisher A686)
1 mL/L 2 g/100 mL dH2O 0.151 mM
4 CaSO42H2O
(Mallinckroft 4300)
30 mL/L 0.2 g/100 mL dH2O 0.35 mM
5 P-IV Metal Solution 6 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.