If you play around with the calculator, you can see the recommended changes for the solution based on nitrate and phosphate levels. Without knowing exact starting and retesting levels it's hard to give a concrete answer.
You can look at it this way - the SS solution is your main 'phosphate' dose, your PF solution is your main nitrate dose without affecting phosphate levels.
If your phosphate levels are 'spot on' and nitrates are high, then you are recommended based on the calculator to decrease the PF solution. If your Phosphate and Nitrate levels are off, then you can expect a recommended change in both PF and SS solutions. If Phosphate leves are quite low and Nitrate levels are quite high, despite a low dose/not dosing the PF solution, then you can expect to need the NF solution at that time.
If you think about what solutions contain which nutrients, you can understand the changes recommended by the calculator easier.
That's what I can figure out without exact numbers, hopefully that makes more sense to you.....it makes it much easier to make recommendations and explain them if specific numbers are given (i.e. you try it out
)