For keeping grey or paint ponies white, some swear by Orvus + blueing + oxyclean in water; rinse; ketchup soak; rinse; leave in conditioner.
We like to use 1/3 wintergreen alcohol to 2/3 water in a spray bottle, with a few drops of cowboy magic shampoo into the bottle, is equally as good as any of the green spot removers.
It’s inexpensive, easy and very effective!
