Can someone please help me combat phpBB3 spam?

you need to bump up the permissions on your forum.  This guide will show you how to do it:

http://www.phpbb.com/support/documentation/3.0/quickstart/quick_permissions.php


Also, I would consider adding a load of words to the banned words lists such as viagra and other words likely to be used by spammers.

your best bet would be to make sure unregistered users cannot post.

Ok, I thought this (above comment) was a given - no? That shows my level of expertise here!

I'll look over the guide. I think I'm OK in figuring out how to edit it,  it's just that I'm not sure what levels I should implement for whom - is all that in the guide?

Thank you

I can't find a reference in the guide to where you filter who can post??

http://www.phpbb.com/support/documentation/3.0/

Section 1.5 and its sub sections deals with all permissions.

Ben

Thanks again