Clearing Old Spam Users?

[ttmw]

Hi, I've had a forum for a while but have never bothered to look at who is signing up really. Now i have around 10000 members and i'm sure most of them are spam.

1. Is there a way to get rid of these members, or at least narrow them down a bit.

2. What methods do you use to stop these? I have a few mods but they dont seem to be working on spam members.

Thanks in advance

[dekaybrown]

For the second question, I use human verification at sign up.

Deciphering the puzzle picture sucks, so I added a simple question...

If the "bot" cannot answer "George Washington" to the question "who is on a dollar bill (US)"

This all but stopped the "bots" (spam software) from posting on my forum, or even joining it.