Canon Pixma using excessive Photo-Blue ink

[Jo Brown]

I have a Canon Pixma T8500 printer which seems to use an enormous amount of ink, despite having the defaults set to draft and mono printing. I rarely print in colour and hardly ever print a photo from either tray. And yet colour ink goes down very quickly. This morning, whilst printing a black and white document, the process stopped halfway through, as the Photo Blue ink cartridge had run out. Could anyone suggest why photo blue (an in fact all the colours) is being used to print b&w docs? I've looked at altering the printer settings on my laptop to use black ink only but the option is not available. Many thanks.