Stacking Filters

Had high hopes of getting out and about today - we went to Truro for a spot of shopping and had a bit of time in the Cathedral. Got some good potential blips here. On the way back to Falmouth, the kids fell asleep, queue camera out! We had intended to go to the beach but again the wind was biting cold so LSW sat in the car watching mw geeking around

This image was a bit of an experiment. I was after creamy skies and water and stacked 2 ND filters onto my polariser. Adjusted settings to give a long exposure time. Now, I am not sure why, because WB was set to cloud) but the end result was a picture with a significant red hue to it. At the computer, increased its saturation and contrast. Perhaps someone can explain why I got the red hue???