M.C.
I've done my own colorant and sealing on my grout. I tried to stay with the white color that was my original grout color, but in time it just got dirty. It is really hard to mop and get in the grout. It seems the dirty water just gets caught in the grout unless you hand scrub the grout. I gave up on the white and just finished restaining it in a darker color. The portion that I finished a few months ago still looks good. I am hoping that this color will stay cleaner looking for much longer.
Hope that helps! I will never go with white or light grout again.
M.