20 vol with toner or rebleach?

I bleached my roots and then toned and most of my hair is WHITE (like purpley-white, which is what I want) and the roots are maybe one level darker and are a light blonde but noticeably yellower. Should I just tone the roots with 10 vol and hope it sticks, or tone them with 20 vol and hope it lifts a level as well as depositing colour, or bleach with 10 vol for a lift and then toner?

Help appreciated :)