Lliver Cleansing and Cats

I have heard that putting chlorella in my cat's food can help cleanse the liver from toxins. Is this true and how much should I use for say a 10 pound cat?

My first question is why do you feel you need to cleanse your cat's liver? Is she/he displaying some signs of liver toxicity like sluggishness, poor appetite, weight loss, jaundice or increased liver enzyme tests in recent bloodwork? If not, your cat has a perfectly good toxin removal system and a body that is hard wired to stay in balance, if it is allowed to do what is programmed to do. The liver of a cat is much different than ours and metabolises foods and drugs in a format that cannot be compared to humans and dogs.
The best thing to do for ongoing health of a cat (or dog) is to feed it a species-appropriate diet, which in the case of a cat as a true carnivore, is meat. Please see the work of Richard Pitcairn, "Natural Health for Dogs and Cats", "The Complete Herbal Handbook for the Dog and Cat" and "cats Naturally" by Juliette de Bairacli Levy and "The Barf Diet" by Ian Billinghurst for further information and recipes.
If you still feel your cat needs to go through a cleanse, I would suggest that you do so under the supervision of a qualified practitioner in your area. This can be a delicate procedure and it is best done in a controlled atmosphere in case the detoxifying programme unearths any pre-existing conditions. Such a practitioner may be found throught the Veterinary Botanical Medicine Association at www.vbma.org.