Question about permitted uri chars, plus signs

[eluser]diego.greyrobot[/eluser]
Hello all, I'm developing my first CI website!
I just have a simple question about the permitted uri characters because i had to add one in order for urlencode() to work.
On a gallery page i use pagination but also filter images based on the venue they were taken
so for example: when u get to the gallery page the url looks like this:

http://localhost/gallery/browse/all

after clicking on a page link it will look like this:

http://localhost/gallery/browse/20

at this point everything is fine, but when a venue link is clicked to see all the images from a certain venue the url looks like this:

http://localhost/gallery/browse/some venue

i had to use urlencode to make that url work but as you know, urlencode adds a plus(+) sign to any spaces in the url, and CI does not permit any plus signs.

is there any security issues or concerns with permitting a plus sign to be in urls?
thanks everyone.