Syrup generally reduces the surface tension of water due to its impurities, which significantly affect interfacial energy. The impact on surface tension depends on the type of syrup, its concentration in water, and the temperature. The discussion references a video that suggests a strong surface tension could allow for unique effects, but it is acknowledged that adding syrup would likely disrupt this. Participants clarify that any additive, including syrup, would lower the surface tension compared to pure water. Overall, the consensus is that syrup cannot increase surface tension without contaminating the water.