Middle School Science Blogging Help

Our district is really pushing social media and social networking, but they never say anything about managing the huge volume of content that can be created. I'm looking for effective ways of implementing social media into my 8th Grade Physical Science Class.

Basically, my idea is that every couple of weeks, I or one of the other two teachers would post one of the essential questions upon which our curriculum is based, and then have the kids respond to that.

My big worry is with managing the volume/appropriateness of comments. I've currently got a setup with Blogger, and I'm wondering if I can swing it with that application or if I should go with something else. Any help would be appreciated.