Hello folks. I'm from brazil so if I didn't write very well, I apologize. I had saw this topic last month, but I don't have time to make this DIY. Today I took courage to buy all the stuff. When I read about the perlite I saw that it's made from silicon trioxide(SiO3) and aluminum oxide(Al2O3) Who much toxic the DIY rock can be with all those silicon and aluminum in our saltawater tank? Thank you very much.