This is how I do it. There are many ways people have cultured phyto so just pick the method you feel will work best for you.
I do however recommend using the proper f2 fertilizer if you are going to put this in the display tank.
Miracle grow and other non phyto fertilizers contain elements not used by the phyto and so you will be dumping those into the tank when you add the culture water.
Nannochloropsis Culture