Cokin magenta color cast?

now I've had a look on around on the internet for the problems i have been experience with magenta color casts. There are several problems i have come up with:

1. Apparently there are later ranges and earlier ranges of ND filters, the later ranges of cokin filters are well known for having color casts whereas the new range don't experience this problem.

2.Different sensors apparently allow certain color's through the sensor and restrict others hence one color being more prominent like the red color cast. better explanation bellow taken from: http://www.talkphotography.co.uk/forums/showthread.php?t=141957

The issue is that the Cokin filters transmit IR light more than visible light. Very long exposures will allow a much greater proportion of IR to visible light through, so the images are tinged with IR light, which the sensor will tend to render as red.

This is why some people have the issue and some people don't. Some cameras have stronger IR filters at the sensor than others, and it would appear that different batches from Cokin have different transmission properties.

 Research taken from discussion website:http://www.talkphotography.co.uk/forums/showthread.php?t=141957