XF 1.1 Board overrun by spam

In the last couple of weeks, I have had an influx of spambots. I have since turned on Manual Registration Approval but 100's of spam bots have beat me to it. They are now delaying their posting for a few days/weeks and now I have to use the Spam Cleaner on a daily basis for 30+ minutes.

Is there an AddOn available that will get rid of them all quickly, and do a good job of keeping them away so I don't need to approve new registrations?