Need coder to help eliminate spambots on phpbb3 site

My website is running phpbb3 and is being swamped by spam and spambots. Nearly 20 a day sign up, despite me adding captcha requirements, eliminating access from all but 10 countries etc. I spend an hour a day deleting spam messages and it is harming traffic on my site. please help! I need a coder to install the latest anti spam bot measures, more powerful captcha requirements or give me any ideas and suggestions that we can implement. The goal is to reduce spam bots to maybe one or two a day. Thanks!