Seachem Flourish

I picked up several years supply of this stuff last night;
unfortunately it doesn't have percentages of the nutrient
constituents. By any chance has anyone run a chemical assay on
this stuff? It probably has lots of iron and trace chemicals
but I wonder if it has enough potassium? Is there a potassium
test kit? Anybody have any ideas as to optimal concentrations
for K? Since the iron concentration isn't given and the dosage
instructions are weekly, I think it quite possible to accumulate
a fairly high concentration of Fe if not tested regularly.
Anybody have any comments on whether the recommended dosages
are high or good? Once my current Fe levels decline, I'll
redose and report the new concentration.