Purifiber is an environmentally friendly filtering agent and a perfect replacement for diatomaceous earth in swimming pool filters. Diatomaceous earth is a known carcinogen and has special disposal requirements. Purifiber is a form of cellulose produced from wood pulp and is non-toxic and biodegradable. Each bag provides instructions for amount of Purifiber required, depending on the amount surface of your equipment. It has been shown that light coatings are more effective than heavy ones. All Purifiber must ship motor freight.