I've never used it. Some say rinse it lightly and other say don't. If it's packed in water like Eco Complete then I would not rinse it. If it's not packed with water in the bag then I'd give it a light rinse. It's suppose to have a clairifier in it so again look to see if there is a bottle to add after filling your tank and if so rinse it. If there isn't a bottle of clairifier then it's added in with the substrate and rinsing the substrate before using will likely wash it away. This is the best advice I can give you.