I don't know if your so used to smelling chlorine that when the chlorine dissipates and you cant smell the chlorine anymore, it seems like it smells bad to you. I don't even know if your city municipality uses chlorine or anything else. But chlorine usually dissipates in a couple of days, especially if the water is aerated. If you have ever been swimming in a swimming pool before you know what chlorine smells like because that is what they use in pools to keep the water clean. But don't expect a
nutrient reservoir to smell like a swimming pool because it shouldn't.