I would recommend doing a thorough search of the subject on the internet. Other search terms are "brush park" and "acadja."
If you are really serious about it, borrow or buy Periphyton: Ecology, Exploitation and Management by Ekram Azim, (
http://www.amazon.com/gp/product/0851990967/ref=olp_product_details?ie=UTF8&me=&seller=). It is pretty pricey, comparable to the average textbook. I haven't read the book yet, but it is highly recommended.
One method used to improve productivity is to stuff manure into the hollow center of perforated bamboo which then leaches out to
feed the periphyton. If you are adding nutrients, you need to be careful to maintain a proper balance.