I have the Oxytetracycline mixing it in a gallon of water for Chickens if the red one is the correct ammount
http://www.tractorsupply.com/tsc/product/oxytetracycline-soluble-powder-6-2-5-oz?cm_vc=IOPDP1
800 mg = 5 teaspoons. That bag will make 12.5 gallons at 800 mg, 25 gallons at 400 mg, and 50 gallons at 200 mg.
-Kathy