Any suggestions to stop sexual spam?

I get the occasional spam on my self hosted blog, but all of a sudden one group has targeted a particular page (they use at least 6 different ips). About 10+ sexual spam comments a day, and growing. (I think it could be getting closer to 30 so far today)

So I deleted that page (which luckily is not a main one), and ensured that all comments were being held for moderation before going online.

But they instantly moved to the new page that replaced the deleted one, even though it has a different name.

My blog on wordpress.com doesn’t have a problem because of the spam protection.

Is there any way I can stop this before it gets worse?

Thanks for your help in advance.

Janet
http://greenesrelease.com