Moderation involves students’ participation to online communities and this is something that only you can encourage no matter how powerful a tool is. If participation is optional not all students are likely to contribute. On the other hand, if it is mandatory or marked it might feel like another task that needs to be done. It would be better to integrate it into your course so that students perceive it as an essential part of their learning. For example, you might start a discussion in class that could be continued online; or instead of asking them to write an essay, you could post a relevant video, ask them to discuss it with classmates online and then write something on this.