So at this level I should not dose Silica the right? If that's the case do I have diatoms rather than dinosaurs? I still have some that stay on sand all the time and some that dissapear at night....don't have a microscope but may have to invest in that ughh.Nope! 1-2 ppm Si is fine. It's plenty for any diatoms to grow and is in the ballpark of what natural levels can reach in the ocean.