Chlorine, a basic ingredient for many household cleaning products, is contained in swimming pool chemicals, such as calcium or sodium hypochlorite, which act as 'antimicrobial pesticides', killing bacteria and controlling algae in the water.Since pool water is open to contamination from the air and all the swimmers in it, chlorine, along with other chemicals such as iodine and algaecide, are added in high concentrations to fight off disease spreading organisms.Blurry vision as a result of freshwater swimming is usually attributed to the cleanliness of the water. Certain types of bacteria and algae can be especially harsh on your eyes. One of the most common is called cyanobacteria, also known as pond scum. Cyanobacteria is often a result of warm, stagnant waters, so the best way to avoid this is to swim in lakes that are sparkling clear and pristine.Prevent irritation when swimming in fresh or chlorinated water by wearing goggles when swimming,especially if you wear soft contact lenses. Dubow says that water can change the way your contact lenses fit, making them too tight and causing eye problems.Flushing your eyes with cool, fresh water after your swim is an easy way to calm any eye irritation. Saline eye drops are also a simple fix for sore eyes, making them an essential beach item for this summer season.