You do not feed the leaves to the shrimp like food, the leaves culture good bacteria to grow on them, bio film per say. Then the shrimps feed on that. As the leaf decays the biofilm will attach to the decaying part and the shrimps will end up eating the decaying leaf as they search for BIO film. It will not go all over your tank, as it does take a real long time to break down.
Also you might not like the Tannis look but it has very nutritional properties to it, anti bacterial, anti fungal and over all helps keep water soft. It is always good to wash them a once over with warm water before you put them in or boil them.
Search the forum for info on them and you will learn how and why they are used.
Last edited by sbarbee54; 01-25-2013 at 06:56 PM.