On Twitter, hashtags help spread news and link conversations. On Google+, hashtags help group together related content. On Facebook, hashtags kill your content? According to a study by EdgeRank, when hashtags are used by businesses on status messages, both engagement and virality drop significantly. While this may be related to the posts that are being tagged, it seems to me that this is really a problem with Facebook’s hashtag system. Unlike Google+ and Twitter, hashtags are not easy to use or browse on Facebook — they also seem disruptive in the news feed — like you’ve just posted a Twitter post without bothering to modify it for Facebook.
Social Times has more analysis:
EdgeRank analyzed 35,000 posts from 500 business pages over the month of July this year. They were shocked by the results. At best, the hashtags had no impact, and at worst, the presence of a hashtag reduced the reach of the posts. Contrast this with Twitter, one of the first sites to use hashtags effectively, 70 percent of brands saw retweets increase with the use of hashtags. – Facebook Hashtags Aren’t Very Effective, Study Says by Kimberlee Morrison