New Line code question \r\n etc.

I've got a php application running on a Unix system and need some help with the new line code. The application reads and saves text in a file from a browser textarea. Also, the text file is occassionally opened and edited via ftp and a regular plain text editor. It appears the new line code is getting screwed up because of the different programs handling the text. [i.e. "\r\n", "\n", "\r"] I'd like to have my code clean up the newline code every pass and standardize it. What new line should I use, "\n" Unix, or what? Thanks.....