What is killing my chlorine?

Author: Mr. Quinton Walter Jr.  |  Last update: Monday, August 4, 2025

Bacteria, algae and microscopic contaminants, such as urine, sweat, sunscreen and beauty products, take a toll on your swimming pool's water chemistry. These substances, when present in your pool water, accelerate chlorine demand and can affect your chlorine's ability to maintain properly sanitized water.

Why is my pool losing chlorine so quickly?

The consistent inability to maintain chlorine levels is also called “chlorine demand” and is most often caused by a high level of inorganic and organic contaminants in the water. Those contaminants force the chlorine to work extremely hard to oxidize them, leaving little chlorine to protect swimmers.

What is eating up my chlorine in the pool?

In particular, algae. Reproducing algae consumes more and more chlorine in the sanitization battle between the sanitizer and contaminants. Phosphates are an invisible problem in swimming pools that brings about many consequences.

Why is chlorine not staying in my pool?

Debris or contaminants from winter or periods of inactivity. Heavy pool usage or high bather load, especially during summer. Biofilm or organic material in the water, such as sunscreen, leaves, or algae. Pool covers trapping chlorine and causing it to dissipate more rapidly.

How do I get rid of bad chlorine in my pool?

The safest and easiest (assuming you are in a hurry to lower the chlorine levels) is to use sodium thiosulfate, but be careful how much you use, or you will need a bunch of chlorine to ``neutralize the neutralizer'' and get the chlorine levels back up where you want them.

Why Your Pool Isn't Holding Chlorine

Can you reverse chlorine damage?

For kids with longer hair that swim multiple times a week, a Malibu Treatment once a month can really help reverse and prevent damage. For the casual summer swimmer, getting a treatment every 2-3 months helps remove the chlorine that has built up on their hair and scalp.

How to lower chlorine level in pool quickly?

There are several possible ways to reduce the chlorine levels to acceptable limits quickly.
  1. Stop automatic dispensers. ...
  2. Take a swim. ...
  3. Remove the sun cover. ...
  4. Add some hydrogen peroxide. ...
  5. Dilute the pool. ...
  6. Add sodium thiosulfate. ...
  7. Get help to keep your pool water clean.

Why is my pool not producing chlorine?

Low/No chlorine production

The factors that affect chlorine levels include the summer heat, poor filtration, bather load, and the frequency of use. It's also possible that the time period you set is too short, the chlorine output level is too low, or the filter needs backwashing.

What causes a chlorine lock in your pool?

Too much Stabilizer: A chlorine lock can occur when you have added too much cyanuric acid, or stabilizer, into your pool water. Stabilizer is a chemical intended to protect chlorine from burning off too quickly from UV rays. If you get too much of it, it can completely block your chlorine and make it ineffective.

How do I fix my free chlorine level in my pool?

Shock Your Pool: The best way to solve low free chlorine levels is through shock treatment. Shocking is a concentrated dose of chlorine added to raise the level quickly and oxidize existing contaminants.

What neutralizes excess chlorine in water?

Sodium ascorbate will also neutralize chlorine. It is pH neutral and will not change the pH of the treated water. Sodium ascorbate is preferable for neutralizing high concentrations of chlorine.

Why is my free chlorine always low?

High levels of organic (leaves, twigs, and branches) and inorganic (suntan lotion, soap, hair products) contaminants are the most common cause of low free chlorine. To prevent low free chlorine resulting from contaminants, complete regular skimming, brushing, and vacuuming to remove debris and buildup.

What happens if you swim in a pool with too high chlorine?

Exposure to over-chlorinated water can provoke eye and skin irritation, lung irritation, and asthma. In addition to being bad for your health, the excess-chlorinated pool can eventually become dangerous. High chlorine levels tend to lower the pH level of the water, making it more acidic.

What eats up chlorine in a swimming pool?

Bacteria, algae and microscopic contaminants, such as urine, sweat, sunscreen and beauty products, take a toll on your swimming pool's water chemistry. These substances, when present in your pool water, accelerate chlorine demand and can affect your chlorine's ability to maintain properly sanitized water.

Why do I have to add chlorine to my pool every day?

This powerful compound is the real bacteria-fighter, destroying the cell walls of harmful microorganisms and keeping your pool water sanitized.

Does algaecide lower chlorine levels?

“The algaecide will [deplete the existing] chlorine level dramatically, so you're going to have to add chlorine on top of it in order to activate the algaecide and to best utilize it in the pool,” Wilbur says. Preventing algae growth is more cost effective than having to treat an algae problem.

Why is the chlorine disappearing from my pool?

The first thing to do is to test the water. It could be chloramines, combined chlorine, high TDS, low cyanuric acid, unbalanced water, phosphates, or nitrites/nitrates. Water analysis will reveal the usual causes.

How can I tell if I have a chlorine lock?

Potential signs of chlorine lock include:
  • A Strong Bleach Smell. This smell is produced by chloramines in your pool which signifies a build-up in improperly-treated pool water.
  • Unequal Chlorine Levels. ...
  • Partially Draining Your Pool. ...
  • Non-Chlorine Shock. ...
  • Chlorine Shock.

How to reverse chlorine lock?

The fastest and most accepted way to break a chlorine lock is by shocking your pool and achieving breakpoint chlorination. This is done by triple shocking your pool with UNSTABILISED CHLORINE. Don't use stabilised chlorine as the added cyanuric acid will worsen the problem.

How can you tell if your pool chlorinator is not working?

The easiest way to ascertain if the chlorinator is working is to make sure the cell is clean by checking the needle or production lights. Ensure there is enough salt in the pool. On the chlorinator box there should be a light or dial that indicates it is working.

Why does my pool keep running out of chlorine?

Basic Checks First: Filter Run Time: Make sure your filter is running for at least 10 to 12 hours total per day, specifically during the daylight hours when the sun is out. Circulation: Check that you have strong circulation while on high speed.

How do I fix the chlorine demand in my pool?

The only way to cure chlorine demand is to give your pool the chlorine that it needs through consistently shock treatments. A general rule to follow is to use 3 pounds of calcium hypochlorite pool shock for every 10,000 gallons of pool water. This may vary depending on the degree of chlorine demand that your pool has.

Can you put too much shock in a pool?

Is it possible to shock your pool too much? Yes—excessive shocking of your pool will keep it at an elevated chlorine level. This will cause irritation of the skin and eyes as well as excessive wear and tear on your pool filter system, including excessive corrosion of all metal parts.

What does baking soda do for a pool?

Baking soda, also known as sodium bicarbonate is naturally alkaline, with a pH of 8. When you add baking soda to your pool water, you will raise both the pH and the alkalinity, improving stability and clarity. Many commercial pool products for raising alkalinity utilize baking soda as their main active ingredient.

Why is my chlorine level not going down?

If you used too much of a chlorine stabilizer, or cyanuric acid, chances are that your chlorine isn't breaking down over time. A chlorine stabilizer is supposed to prevent the sun from deteriorating chlorine before it can do its job, and that's important. But chlorine should break down eventually. It's only natural.

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