Citrus Lemongrass Tonic – Refill. Top up your diffuser and keep the freshness flowing with this easy refill. Bursting with the same crisp blend of citrus and lemongrass essential oils, it brings clean, energising scent back into your space. Made with natural ingredients and free from synthetic perfumes, it’s a simple way to make your favourite diffuser last even longer. Just pour it in, pop in your reeds, and enjoy the brightness all over again.