I do not recommend giving your chin a vitamin or mineral supplement in their water. These products sold at pet stores can cause problems since adding them to water can cause bacteria to form very quickly. Your chin should get their vitamins from food sources such as their pellets, hay or natural supplements/treats. Rosehips for example are one of the highest forms of natural Vitamin C you can find and chins love them. Many herbs and grains have vitamins in them that are safe and healthy to give your chin as a dietary enhancer.