When buying replacements, be sure to buy only reed. Neither bamboo nor wood will work in a diffuser.
A reed diffuser -- a decorative bottle of scented oil into which reeds are placed so they stick a few inches out of the top -- is an attractive way to scent your home. The reeds draw up the oil and freshen the air in the room. You don't light them like a candle, so there's no fire danger or soot particles in the air. They don't run on electricity, so they save energy. And they last for months when you turn the reeds over once a week. But they don't last forever. Easily replace the oil and reeds yourself.
Throw away the old reeds after about 6 months of use. They'll be completely saturated with oil and you can't wash them thoroughly enough to use forever, especially if you're using a different scent. New reeds are inexpensive -- 30 reeds for about $3 in 2010. Purchase them from your local craft, home improvement or discount store.
Wash the bottle thoroughly with dishwashing liquid and hot water and allow to dry. If you're changing to an oil with a different fragrance, you may need to soak the bottle and wash it more than once to completely remove the scent.
Wash decorative items, such as rocks, that were in the oil in the bottle with dishwashing liquid and hot water. If you're going to use an oil with a different scent, and you can't completely remove the smell from the decorative pieces, replace them.
Add new scented oil and reeds to the bottle.