I found this helpful. I use the Duramyicin
In this case, 6.4 oz equals 181.4 grams and measures 7/8 of a cup. There are 2 TBSP or 6 tsp per 1/8 cup. If there are 42 teaspoons in this 181.4 grams, then there are 4,319 milligrams in each teaspoon of this powder.
Then since you have the different dosages between 400-800 mg, just adjust based on the 4,319mg/tsp. So 1/4tsp will give you 1079.75 mg so an 1/8tsp gives you 539.88 (which is what I use). So 1/8 tsp to a gallon. New solution mixed every 24 hours.
M