Thanks for your help DB.
I did some more research. It turns out that guaranteed analysis is reported in elemental percentages for commercial fertilizers regardless of the chemical used.
So in this example Flourish Iron is 1% elemental Fe.
Here is the article
that explains all of this including the formulas to make the calculations. The calculations are actually much easier than what I had originally thought.
Here is the basic formula presented there.
Amount of fertilizer to make 1 volume of stock solution = Desired ppm x Dilution factor / % of element in fertilizer x C
C are the constants listed below. The dilution factor can be used for making solutions or omitted for direct fertilization.
Ounces per U.S. gallon 75
Pounds per U.S. gallon 1200
Grams per liter 10
Oddly enough this formula seems to work out for premixed solutions as well such as Flourish products etc.
Example, If we want 0.5ppm of Fe in one liter using Flourish Fe
0.5ppm / 1% * 10 = dose
0.5 / 10 = 0.05
dose = 0.05ml/liter
For 10 gallons (37.8544L * 0.05) that's 1.89ml
Now if I can figure out how to calculate oxidized portions such as NO3 versus total nitrogen or P vs PO4 it will make life much easier lol. It appears that you add the oxygen portion of the molar mass to either P or N. However, I’m not sure that works out all of the time.
Edit: Never mind the total nitrogen versus Nitrate question. It's simply the molecular weight differences. Sometimes I miss the obvious lol