around 110 hours Click to see full answer. Thereof, how long does it take for chlorine to evaporate from water for fish?2 PPM (Parts Per Million) levels of Chlorine will take up to 110 hours to evaporate completely from about 10 gallons of water. It is important to note that certain conditions such as Ultraviolet light rays, aeration, and proper circulation will speed up the evaporation of chlorine from water.Also, how do you remove chlorine from water naturally? You can remove chlorine from your tap water by using a Granular Activated Carbon (GAC) filter that will absorb and trap most natural organic compounds, tastes, odors and synthetic organic chemicals. Thereof, does chlorine dissipate over time? Chlorine doesn’t evaporate; it breaks down, aided by UV light (sunlight). It takes about 24 hours for the water to become mostly chlorine-free. But your real problem is Chloramine. Chloramine doesn’t break down in UV like chlorine, and can last up to two weeks.Does chlorine dissipate in a closed container?If the top is not sealed, the chlorine will leave the water. Several years ago before instant chlorine removers were available for fish tanks, the solution was to fill the tank with water and let it sit for 24 hours.