High Nitrogen Levels in Swimming Pools

Sources

• Nitrogen can enter the pool water from a variety of sources. Swimmers release nitrogen contained in sweat, urine and other bodily fluids. Fertilizers are also a major source. Nitrogen is one of the macronutrients needed for plant growth, and most fertilizers contain high levels of the nutrient. Fertilizers that are applied to the lawn and garden nearby can easily be picked up by the wind and dropped into the pool as well as being swept in by rain and runoff.

Potential Problems

• High levels of nitrogen in pool water can make it difficult to keep the water appropriately sanitized. Nitrogen will combine with chlorine and bromine to form chloramines and bromamines, tying up the chemicals that would otherwise be available to kill organisms and bacteria in the water. This can lead to the development of algae, eye irritation or even make the water unsafe to swim in.

Pool Shock Treatment

• Adding chemicals to the pool will lower high nitrogen levels. Oxidizing chemicals will break down the nitrogen as well as ammonia. One of the most common methods used is chlorine "shock." Shock will also break down pollutants that contain nitrogen, such as urea and the compounds found in fertilizers. If high nitrogen levels aren't discovered until they have been present in the water for some time, it may also be necessary to add algicide to the water. The combination of shock and algicide will help restore the pool to a balanced, healthy state.

Prevention

• Nothing can keep nitrogen totally out of the pool, but shocking can be done periodically to prevent nitrogen levels from becoming too high. Consider factors such as how often the pool is used and how many swimmers are regularly in the water -- the higher the use, the more nitrogen is being introduced, and the more often shock should be added. Check the sides and bottom of the pool regularly as well. If they seem slippery, this is an early sign of developing algae.