i have a product similar to this in my fuge, aptly titled refugium mud. my chaeto has been growing better. not great, but i account that for lack of high flowing water. i put a good 3 inch base and then covered that with another 3/4-1" of crushed aragonite, just like the product says. it states that it should reach anaerobic conditions and such. i just did it, exact benefits unknown, i just know it didnt hurt it. copper is found in NSW, but mind you TRACE amounts (ppb). www.thomasnet.com/pdf.php?prid=10042 (ive decided to source everything i post....lesson learned) so minute amounts of copper seem to be more aimed at achieving ocean water balance. i doubt it would be enough to harm your corals or inverts.