How display checked filter variable value in url

I am a basic user of code igniter and PHP.I have some products page with filters. How to created a URL link like this:

Code:

http://somepage.pl/products?color=red

I know I can do above url when I will change the config line:

Code:

$config['enable_query_strings'] = FALSE; on TRUE.

But I want to use this option only one controller and one function.
I can write same code whitch it will filter this products by color for example, but I want create link like on top. People will be able to share this link.