Just to be clear, when it says how much to dose, are the results those of a one-time dose, or do I need to divide by 3 to get what I should really dose?
If I take the amount of PO4 I dose and multiply times 3, then my resulting concentration is 3.94 ppm, which is too high. By this standard, the dosage of K gets 23.34 ppm and NO3 gets 4.68 ppm. Does this sound right?
Let me explain by way of an example:
I have a 29 gal tank, so I put 26 gallons into the calculator (estimate of actual water volume). I select KH2PO4 and leave the "I AM CALCULATING FOR" drop-down on "Estimative Index" and "Dry Dosing" for simplicity sake in this example. Hit "Calculate" and the results appear on the right, which include how often to dose the amounts.
Now, you note the ppm level for each dose (these are single-dose numbers). So, e.g.; PO4 is 1.3 ppm. Then, you go to the "Accumulation Calculator." Once there, you put the 1.3 ppm into the "Dose' section, select your dose frequency (2 days, which is every other day), water change amount (50% as per EI recommendation) and how often (every 7 days which is once a week). Hit "Show" and you will see the range of PO4 that this dosage will build to, in your tank, after a few weeks.
In the "Accumulation Calculator", you can now decide if that is the level you want. In this case, it is showing an average in the 6 ppm area. However, let's say you want it to be in the 2 ppm area. So play around with different "Dose" levels here. Finally, you find that .4 ppm gives you the 2 ppm average you want.
Now, you go back to the "Nutrient Calculator" and set everything as before. However, this time you select "Dose to reach a target" instead of "Estimative Index" in the "I AM CALCULATING FOR" drop-down and put the .4 ppm that you found in the "Accumulation Calculator" into the "MY TARGET IS: PO4" section. Hit "Calculate" and the amount to dose each time is shown as 72 mg. Recall from the "Accumulation Calculator" that you chose three doses per week. So, you now know to dose 72 mg, 3x per week, and you will achieve roughly 2 ppm with 50% weekly wc's. Of course there will be plant uptake that is not accounted for, but this will get you into the ballpark of where you want to be.
If you want to put the PO4 into a solution for easier dosing (where you can also combine all three macros), you can just select "A Solution" instead of "Dry Dosing" and rework the numbers.