The allelopathic potential of macrophytes is extremely significant in shallow waterbodies in semiarid areas, such as the Mediterranean, where the shortage of them makes wetlands, lagoon or coastal; ponds essential aquatic ecosystems. It is also known that allelopathic effects of a macrophyte can be species-specific and this, the resistance or vulnerability of phytoplankton to macrophyte in the field will depend on the composition of both. Our goal is to investigate the allelopathic potential of charophytes that have not been studied previously in this sense (C. hispida, C. baltica, C. vulgaris, and N. hyalina) on microalga assemblaga in order to determine what type of charophyte or combination of them promotes clear water conditions through alleopathy.