From Reefing Art Team: Our media uses 100% aquarium safe non-metallic ceramic, will not leach aluminum or any heavy metal. Bio filtration does not build overnight. Please allow 7~21 days for beneficial bacteria to build and establish. Customer may use bacteria booster products to expedite the process. (Note: fresh and saltwater have different types of bacteria, please choose the correct bacteria booster for your aquarium) We try our best to ensure the product arrives to you safely, however damage may still occur due to mishandling. Minor chip or crack will not affect the effectiveness of the media. If the media arrives to you with significant damage, please contact our Reefing Art Customer Support Team.