Why does my swimming pool water smell like bleach or chlorine when the pool water chemistry is balanced and the filter is clean?
The most common cause of smelly swimming pool water is an accumulation of chloramines in the water. Whenever someone swims in the pool they leave behind some contaminants like deodorant, sunscreen, sweat, saliva, urine and faecal matter. Other contaminants like bird droppings, insects, flowers, seeds, leaves, bacteria, viruses and algae fall or blow into the pool. These contaminants decay into ammonia and nitrogen molecules. Chloramines result from the combination of pool chlorine and contaminant ammonia and nitrogen molecules in the water.
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Why Does My Pool Water Smell Like Bleach?
When your swimming pool smells bad most people think it’s caused by too much chlorine when in fact it’s the opposite issue.
There is too little chlorine in the pool water.
The bad smell is actually caused by contaminant ammonia and nitrogen compounds in the water. Remember your high school chemistry – bleach contains ammonia. So when the pool smells like bleach it’s the ammonia that you are smelling.
The smell of bleach or chlorine in the pool water is the first sign that there is something not right with your pool sanitation. Most likely you have a build-up of chloramines in the pool water.
What are Chloramines?
Chloramines are the chemical residue after free chlorine has reacted and bound with dirt, sweat, oils, sunscreen, urine, bird droppings, decaying insects, bacteria, algae and anything else that invades your pool water. If you pool water smells bad then you have too many chloramines in the water.
When there are chloramines present in the pool water you need to take action to eliminate the problem. Chloramines build up in the water making it easier for bacteria and algae to multiply and take over the pool. Chloramines have been linked to skin rashes, red eyes and respiratory problems like asthma.
Is the Pool Safe for Swimming?
Always use common sense before swimming in a pool or bathing in a hot tub.
Smell the Pool Water
When there is a pool water smell of bleach or chlorine do not swim in the pool. The water is not correctly sanitized and may contain harmful bacteria and algae. Swimming in this water may cause skin irritation, red eyes and many other health problems.
Look at the Pool Water
The pool water should always look clear and clean. You must be able to easily see the bottom of the pool. If the pool water looks dirty, colored or cloudy do not swim until the water is clear again.
Touch the Sides of the Pool
When you touch the pool surfaces are they slimy or greasy? If so, the pool has a sanitation problem and you should not swim until the problem is resolved.
Warning: Do Not Taste Pool Water
Don’t taste swimming pool water to determine if it is clean. Your sense of taste will not tell you anything about the chemical composition of the water. Never swallow pool water as it contains chemicals and residue chloramines which are harmful to your health.
How to Remove Chloramines from Your Pool
Chloramines is the result of a low level of free chlorine in your pool.
There is not enough free chlorine in the water to neutralize all the contaminants.
What is Free Chlorine?
Free chlorine is simply the chlorine that is available in the water to kill bacteria, viruses and other contaminants. The free chlorine is either added manually, by an automatic dispenser or by way of salt water chlorination.
The recommended free chlorine level for a swimming pool is:
Free Chlorine 1.0 – 3.0 ppm
How to Measure Free Chlorine
Expert Tip: Get test strips that measure free chlorine, not total chlorine or combined chlorine.
Use a pool test strip as follows:
- Take a test strip and dip it into the pool water for 5 seconds.
- Remove the strip and wait 10-20 seconds.
- Compare the colors on the strip to the label on the container.
- Record your readings
The common swimming pool strips test – Free Chlorine, pH, Total alkalinity & Stabilizer.
Shock the Pool Water
Shocking the pool water adds a large dose of free chlorine to the water and eliminates chloramines to keep your pool water sanitized.
Frequently shocking your pool with a chlorinated product must be part of your maintenance routine to ensure you have a safe, clean pool for your family and friends to enjoy throughout the summer.
Warning: Before you handle any pool chemicals make sure that you are using protective clothing and gloves. I recommend a mask and eye protection as well. Try not to add chemicals to your pool when there is a breeze as you might end up wearing the chemicals.
Most shock treatments are a powder or granular chemical that comes packaged in a one dose pack which is the correct size for the average backyard pool. Normally, you can spread the shock around over the pool surface.
Carefully read the manufacturer’s instructions to ensure you are applying the shock correctly for your pool.
Test the water the next day to make sure the pool is still balanced, otherwise adjust chemistry levels as required.
Shock treatments can cause the pool water to look cloudy for a few days. This is normal and will dissipate over the next few days as the free chlorine reacts to other compounds in the pool.
Which Shock Treatment to Use?
The most widely used shock treatment is calcium hypochlorite.
If your calcium level is already high don’t use shock containing calcium hypochlorite as this will make it worse. Use lithium hypochlorite or sodium hypochlorite instead.
Some products can be directly added to the pool water whereas others are best mixed into a bucket of water first. Always follow the instructions on the packet.
Expert Tip: Add the shock to the pool in the evening when the sun has gone down. Sunlight rapidly evaporates chlorine making the shock less effective. Ensure the filter pump is operating to circulate and mix the shock into the pool water. Do not swim in a pool that has just been shocked. Wait until the chlorine level has returned to normal. Usually the next day the level is back to normal.
Please read our article on The Ultimate Guide to Pool Chemistry
How to Prevent Chloramines in Your Pool
Now that you have shocked your swimming pool and eliminated the chloramines you will want to keep it that way.
To prevent problems arising follow your pool maintenance routine.
- Ensure that all your other pool chemistry indicators (pH, salinity, alkalinity, stabilizer, TDS, etc.) are correctly balanced before adding shock.
- Add cyanuric acid to the water to stabilize and extend the chlorine’s useful life in the pool. Stabilized chlorine will last 3 to 4 times longer than unstabilized chlorine.
- You may need to add a dose of shock every week in the summer to prevent the return of chloramines.
- If your pool is saltwater chlorinated you may want to turn up the chlorine production on the chlorinator control unit.
- Clean your saltwater chlorinator cell every year. Replace your cell if necessary,
- Freshwater pools may need more frequent chlorination by increasing the dosage from your automatic chlorine dispenser.
- Add a floating chlorine dispenser to the pool to give it the extra boost it needs.
- Clean the filter more frequently, especially in the summer months.
- Maybe it’s time to purchase a new filter cartridge. They usually begin to fail in the summer season with the extra workload.
- Always shower before entering the pool to reduce bodily contaminants getting into the pool water.
- Don’t swim if you have any open cuts or abrasions on your skin.
- Always wash your dog before it swims in the pool.
Conclusion
Pool water should normally be odourless and never cause athlete’s foot, skin rashes or red eyes.
When your pool water smells like bleach there is no enough free chlorine or other sanitizer in the water.
Don’t worry as there is a simple fix – shock the pool to raise the free chlorine level. Free chlorine will neutralize the ammonia and nitrogen compounds eliminating the bad smelling pool water.
If you don’t want to use chlorine there are other options like bromine or Biguanide.
Check out our other posts on this site to help you better manage your pool maintenance and reduce the time and effort to operate your pool. After all, you want to spend more time in your pool rather than maintaining it.