wash them off with bleech and water like 1/3 bleach to 1 whole water. wash them off and or soak them keep repeating until they are clean, and then rinse them off with a lot of plain good water.

Is the hyrdoton stuck in the roots if so, just start shaking them out they should come out with out you having to pull each one individually. Its tricky and probably time consuming, you could cut them out in sections. Its gonna be messy i can see it already.