I have just purchased some Hibibscrub for Ollie has he has got some acne under the chin. Could any one please help me with how to use it. I am assuming I have to dilute this but I don't know how much to water. I have bought some very soft tooth brushes to apply it with. Ollie is a red silver Tabby so I don't know being a red if there skin is more sensitive. Ollie is 9 months old.