Any source of clean water fresh or salty will do. When you are not actually using a crystal, assign it's home on the cluster. I recommend a cluster as big as your budget can possibly muster or at least one the size of a saucer. The cluster itself will require attention from time to time so keep a thought for it to. The use of smoke to cleanse crystals is a tradition of the American Indian shaman.
Smoke permeates the etheric and is able to 'dissolve' ambient charge in an environment.
Fresh plain sea salt will draw charge like a poultice from the crystal. You need enough salt to bury the crystal wholly within a jar. A few drops of water to get good contact then leave it be for at least 3 days. It's quite a wasteful means as the salt can be used but once for this. This means is by far the most direct and instant solution.