Managing Chloramines and Pool Odor
Why a 'smelly' pool actually needs MORE chlorine.
We've all been to a hotel or public pool that has a strong, stinging 'chlorine smell.' Most people think this means there is too much chlorine in the water. In reality, it's the exact opposite. That smell is caused by Chloramines—chlorine that has combined with sweat, oils, and urine. A smelly pool is a dirty pool that needs a massive dose of fresh chlorine to 'break' the chemical bonds and clean the water.
Free Chlorine vs. Combined Chlorine
Free Chlorine (FC) is the hero—it's active and ready to kill germs. Combined Chlorine (CC) is the 'spent' chlorine that is no longer effective. Total Chlorine (TC) is the sum of both. If your TC is higher than your FC, you have chloramines. A healthy pool should have a CC level of 0.2 ppm or lower. Anything above 0.5 ppm requires action.
The Irritation Factor
Chloramines are responsible for red eyes, itchy skin, and the distinct 'pool smell.' They are also poor sanitizers, taking up to 100 times longer to kill bacteria than free chlorine. If your swimmers are complaining of eye irritation, don't lower the chlorine—test for chloramines and prepare to shock the pool.
Breakpoint Chlorination: The Math of the Shock
To get rid of chloramines, you must reach 'Breakpoint Chlorination.' This requires adding enough chlorine to reach a level 10 times the amount of combined chlorine. If you have 1.0 ppm of CC, you need to raise your FC to at least 10 ppm all at once. This massive surge breaks the ammonia bonds, allowing the chloramines to gass off into the air.
Indoor Pools and Air Quality
Indoor pools struggle with chloramines because there is no wind or sunlight to help the gases escape. High chloramine levels in the air can cause respiratory issues and corrode metal deck equipment. High-quality ventilation (HVAC) and the use of UV or Ozone secondary systems are the best ways for indoor facilities to manage the chloramine burden.
FAQ
Can I use 'Non-Chlorine' shock for chloramines?
Yes. Potassium Monopersulfate (MPS) is an oxidizer that 'burns off' organic waste and chloramines without raising chlorine levels. It's a great choice for indoor pools or for when you want to swim immediately after treatment.
How do I prevent chloramines?
The best prevention is swimmer hygiene. Enforce a 'shower before you swim' rule to remove sweat and oils, and strictly educate children (and adults!) not to urinate in the pool. Ammonia from urine is the primary building block of chloramines.
Does sunlight help with chloramines?
Yes. UV rays from the sun naturally break down chloramines. This is why outdoor pools typically have fewer odor issues than indoor pools, provided they are properly maintained.