How to add a hashtag to a tweet link
Go to the Share Link Generator.
Put in your tweet you want to be able to share through a hyperlink.
Take the “URL Only” output code, then add this magic:
%20%23Hashtag
Where Hashtag is what you want your hashtag to be.
So your final hyperlink anchor will be:
http://twitter.com/home?status=Your%20text%20here%0yourdomain.com%20%23yourhashtag