WC(ed) formulation | Canadian Phycological Culture Centre

Add stock solutions as indicated below to 900 mL of purified water and make up to 1 L. Adjust the pH to 8-8.5 as needed.

Stock	Substance	Concentration	Amount added to medium (mL/L)
1.	CaCl₂•2H₂O	36.76 g/L	1 mL
2.	MgSO₄•7H₂O	36.97 g/L	1 mL
3.	NaHCO₃	12.6 g/L	1 mL
4.	Na₂SiO₃•9H₂O	28.42 g/L	1 mL
5.	Ca(NO₃)₂•4H₂O	4.13 g/L	5 mL
6.	NH₄NO₃	10 g/L	4 mL
7.	K₂HPO₄	8.71 g/L	1 mL
8.	Trace metal solution	See below	1 mL
9.	f/2 vitamin solution	See below	1 mL

Trace metal solution

* Make up asterisked compounds below as primary individual stock solutions in g/L and dilute 1000x as follows: add 1 mL of each of these stock solutions to 900 mL of purified water; add remaining compounds (as mg/L) and make the final trace metal solution up to 1000 mL.

Substance	Concentration (mg/L)
1. Na₂EDTA•2H₂O	4360 mg
2. FeCl₃•6H₂O	3150 mg
3. ZnSO₄•7H₂O	22 mg*
4. CoCl₂•6H₂O	10 mg*
5. MnCl₂•4H₂O	180 mg
6. Na₂MoO₄•2H₂O	6 mg*
7. CuSO₄•5H₂O	1 mg*
8. H₃BO₃	1000 mg

f/2 vitamin solution

Substock solutions:

First prepare separate substock solutions of cyanocobalamin (Vitamin B12) and biotin in purified water (e.g., Milli-Q, Nanopure, distilled water).

Substock	Substance	Concentration
1.	Vitamin B12 (Cyanocobalamin)	10 mg/10 mL
2.	Biotin	5 mg/50 mL

Working stock solution:

Then prepare the final working solution by combining the following amounts of the two substock solutions plus thiamine HCl to 100 mL of purified water.

Substance	Concentration (per 100 mL)
1. Vitamin B12 (Cyanocobalamin)	0.1 mL
2. Biotin	1.0 mL
3. Thiamine HCl	20 mg

Dispense the working solution as 1 mL aliquots in cryovials for convenient use when preparing the medium. Store the remainder of the primary stocks and working solution in polyethylene bottles. Wrap vials/bottles with Parafilm to avoid moisture loss and store all solutions frozen.

References: Guillard and Ryther 1962, Guillard 1975