Abstract: A composition is provided containing powdered cellulose and at least one water insoluble, immobilized water treatment additive. Preferably, a filter media composition is provided containing powdered cellulose and at least one water insoluble, immobilized enzyme such as lipase for filtration of swimming pool and spa water. The lipase may be recombinantly produced, and lipases having 1,3 positional or non-positional specificity are used. The immobilized lipase may be in the form of bead-shaped particles, and immobilization can be on a macroporous acrylic resin. Moisture may be added to the composition to provide a pre-moistened composition that is dustless and provides for improved dispersement and even filter grid coating. In a filtering system, the filter media absorbs oils contained in pool or spa water, and the lipase hydrolyzes the oils.