actually fellows there is a product called "wesleys bleech wite" < i think thats how its spelled!
its used to keep the white wall tires white!
you can find it in any automotive parts stores just go in and ask for (pronounced) wesleys bleach white!~
heres a plus it wont harm the plastic anyway shape or form!
and something even better if you go get "pantyhose"... yes i said it "pantyhose" you can use that as a filter and just reuse the stuff over and over and even over!