The invention relates to an antibiotic aid (in particular an antibiotic aid for the preservation of cut flowers) comprising: 1) an ion-exchange material loaded with antibiotic ions (preferably silver ions) and 2) an anion sink, An anion sink is preferably an anion absorbent (or adsorbent) or a container with porous walls (said walls permeable to water and metals ions but impermeable to salts of antibiotic metal ions).
