Powdered MSU Fertilizer Into A Liquid Concentration?

[NiNiDazzle]

I have a few pounds of the MSU fertilizer for RO water that I turned into a liquid concentration according to First Ray's site.

Question 1
There are still particles that will not dissolve no matter how much I shake it. Do I need to add more water to the solution to try to get it dissolved or is it ok the way it is?

Question 2
Now that I have it as a liquid concentration, how much should I use for a gallon of RO water for S/H? I would assume that it would be 4 teaspoons per gallon, but since I will be watering it weakly/weekly, or in my case, every 2-3 days, should I be using half strength, quarter strength...?

Thanks for any help.