KITA Fragrances Reed Rattan Reeds replace your saturated reeds. Your reeds should be replaced when:
you need to refill your diffuser with a new fragrance so that you do not produce undesirable scent combinations, OR
you have used the same reeds for the last 2 refills. After two refills with the same rattan reeds, the reeds will become saturated and the liquid will be unable travel up the reeds causing the fragrance to have a smaller throw and even distorting the scent.