Combine the KH2PO4 and the distilled water adjusting
the pH to 6.8 using NaOH. Autoclave at 121ºC for 15 minutes and cool the
medium to 56ºC. Filter sterilize solutions 1-4 and the trace element
solution. Aseptically add them one at a time to the autoclaved solution.
FeSO4 x 7 H2O
MgSO4 x 7 H2O
Solution 4 may not go completely into solution. It may be necessary to
shake or sonicate to break-up the clumps. The final concentration needs to
be between 100-500 µg/ml. Shake well and filter sterilize.