That's the problem with antibiotics that have to be mixed in water, but sometimes there isnt much choice. A sick chicken wont drink or drink enough of the treated water or enough of it to be effective. I would recommend dosing with a full syringe (without needle) of the mixture at least 3-4 times a day for however long the recommended treatment lasts. If you dont do this, the chicken wont get better and health will deteriorate.