If they are telling you that two tablespoons per gallon will give the same nutrient level as one teaspoon of the powder, then you would have to weight the teaspoon of powder, then weigh the two tablespoons of liquid to know the true percentages.
However, I think that if you estimate 1/6 (two TBSP = 6 tsp), you'd be in the ballpark, making it roughly a 2-0.5-2.5.