Personally, I would use less than that. Maybe 1/4 cup or something. I would be careful with potassium sulfate and mineralized phosphate. All the meals are pretty mild but I don't have a lot of experience mixing up mineral salts. I imagine they're really soluable and might mix up strong.
I usually mix 3 teaspoons of kelp and 3 teaspoons of alfalfa into 5 gallons of water, so I may be kind of a conservative puss tho.