Not long ago I installed a new plugin for the forum called Cleantalk to help manage the amount of spam accounts that I was having to deal with every day. It managed to block a few hundred right away and I was able to monitor it relatively easy so I decided to fork out the money for 3 years of their service. There have been a couple false positives, but I was able to handle those with a lot less hassle than it used to take me every day with all the bot accounts and spam posts I had to fight. In the process I was also able to get the SSL certificate for the site created and installed, which took a little doing on its own but has proven to help so far. In the end, if you find yourself managing a forum and you're having trouble with spam then give them a look see. They've got plugins for most of the popular forum and wiki base software suites.
https://cleantalk.org
