It does fine in low or medium light. In fact I often find it growing places where it must get hardly any light at all, such as swamps with heavy growths of floating plants and filamentous algae at the surface. Hornwort is pretty versatile as far as water parameters, but doesn't like sudden changes in parameters. So it's best to acclimate it to your tank water just like you would a sensitive fish, and try to avoid huge water changes.
