Is there a way to completely remove spammers from a hashtag?


Hello there,
We are college that uses twitter as a mean to get in touch with our students
Recently a huge number of spammers are using the same hashtag we are using
Is there an effective solution for this problem, as we are no longer able to track student’s responses though the hashtag easily
We already tried the report for spam an block but it still turns up in the search result in the hashtag
Please let us know how to fix it,
Thank you,