Originally posted by Bactman 
I've also been exploring using the Cokin P series, and one issue that keeps popping up is the magenta hue some users have noticed when using ND filters. The magenta cast can't be removed during pp. ND filters are supposed to be color-neutral, not add color. The next step would be the more expensive (and higher quality) NDs from Singh Ray or Lee (I think).
Good luck.
I use Singh Ray's pretty much exclusively and have never had an issue with magenta. Cheaper filters can be just that...cheap. I started with cheaper filters years ago and could never figure out why I wasn't getting the image quality I thought I should be getting. I experienced color degredation with most of the cheaper ND's but can't recall magenta being an issue (doesn't mean it wasn't...I was new at it back then!)
Singh Ray's are indeed expensive, but you really do get what you pay for in this instance. The cheaper ones are great for learning how to use ND's (and there is a learning curve), but if you are truly in it for image quality and professional results, filters are one area where spending the extra money is worth it. The first time I used a Singh Ray ND, I was sold.
Similar Threads 
