Dosage: 25mg THC 25mg CBD per can – Tonic Fizz Seltzers are the newest addition to the Tonic family. Crisp and refreshing, each can of Tonic Fizz has 25mg THC. Grapefruit Tonic Fizz, grapefruit flavored with natural ingredients, has zero calories and zero sugar. – Ingredients: Carbonated Water, Natural Flavor, Potassium Sorbate, Citric Acid, Sodium Benzoate, Gum Arabic, Pure Cannabis Oil, Stevia.