Go to replies div on redirect

On my forum when a user replies to a thread / post

I am trying to be able to get it to go to that div once created.

PHP Code:

redirect(base_url('viewthread?tid=') . $tid . '#' . $pid); 


Code:

http://www.project.com/viewthread?tid=1#14

But for some reason will not go to the div.

It will go to div if have a space before hashtag

PHP Code:

redirect(base_url('viewthread?tid=') . $tid . ' #' . $pid); 


But then the url produces 

Code:

http://www.project.com/viewthread?tid=1%20#14

How can I make it go to the div with out having space in the url?

There's only one rule - please don't tell anyone to go and read the manual.  Sometimes the manual just SUCKS!