Grey Water Plants And Substrate

Hi,
I have a question regarding the plants and the media used for the roots in a natural grey water filtration system, what are the best plants selection that are fast growing? can plain gravel be used as a media for the roots, is there other options?

this has been covered previously, have a search around.
Plain gravel is ok for many plants but a food filter at the start extends the life of the bed.
The plants vary for your location.