Will chlorine level go down by itself?

Author: Prof. Isom Armstrong DVM  |  Last update: Tuesday, September 2, 2025

Not using your hot tub until chlorine levels go down by themselves is the easiest method. All you have to do is let the water evaporate, and the chlorine will dissipate. Chlorine concentration will naturally decrease if the hot tub is not in use.

Will chlorine go down on its own?

Just Wait it Out. Chlorine will burn itself off naturally. Depending on how hot it is and how high your chlorine levels are will determine the amount of time needed. It could be quick or it could take a few days.

What to do if total chlorine is too high?

If it's extremely high, you can dilute the entire pool chlorine level with thiosulfate, which is chlorine neutralizer, but it's fairly expensive and I only recommend using it if you have to lower the chlorine level very quickly for emergency reasons, otherwise it will come down slowly on it's own over a few days.

Does chlorine level drop?

Chlorine will get used up naturally, and its levels will get lower over time.

Is it OK to swim if the chlorine is a little high?

The maximum safe chlorine level is 3 parts per million (ppm). Anything above 5ppm is considered a hazard and should be addressed immediately. If you find numbers as high as 7-10ppm, the pool should not be used until chlorine levels return to safer levels.

How To Lower HOT TUB CHLORINE or BROMINE Levels

How to lower chlorine level in pool quickly?

Use Hydrogen Peroxide.

Pool-grade hydrogen peroxide reacts with chlorine to produce water and oxygen. Just be sure to test your pH before adding it. It works best at pH levels of 7.0 or higher. It will also lower your pH after using it, so be sure to test and adjust your levels then too.

How long does it take for chlorine to evaporate from water?

If you are sure your tap water contains chlorine and not chloramine, you can let the water sit for 1-5 days to allow all the chlorine to evaporate. To speed up the evaporation process, aerate the water with an air stone for 12-24 hours or boil the water for 15-20 minutes.

How fast does chlorine go down?

In most cases, it takes 24-48 hours for chlorine concentration to drop significantly. If the water is too hot or the chlorine levels are too high, it may take longer for the chlorine to evaporate. You can speed up the process using a chemical oxidizing agent or diluting the water with fresh water.

Will rain lower chlorine in pool?

More water in the pool = lower concentration of chlorine in the pool. Rainwater also lowers chlorine by collecting pollutants, particles, and other contaminants in the air on its way down and delivering them into the pool or spa water.

Why won't my chlorine level go 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.

Does shock lower chlorine levels?

Shock is chlorine, in a high dose, meant to shock your pool and raise the chlorine level quickly. Chlorine tabs (placed in a chlorinator, floater, or skimmer basket) maintain a chlorine residual in the water. You do need to use both tabs and shock.

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.

What if chlorine level is high but still have algae?

Proper circulation and filtration are vital to prevent algae growth. Stagnant water provides a breeding ground for algae, even if chlorine levels are high. Ensure your pool's circulation system works correctly, and clean or backwash the filter regularly.

Can I swim if chlorine is 10 ppm?

When free chlorine is over 5.0 ppm, swimmers may experience itchy skin, irritated eyes, and/or dry hair. Pools will naturally gas-off chlorine from the surface, and very high levels can irritate airways and lungs. This is especially true for indoor pools. At chlorine levels over 10 ppm, swimsuits can begin to fade.

How long does it take to neutralize chlorine?

Typically, if left exposed to air in an open container, chlorine will naturally dissipate within a few hours to a day. Boiling water for 15 minutes also helps to remove chlorine as it causes the chlorine to evaporate.

Will baking soda lower the chlorine level in the pool?

She says: 'Contrary to popular belief, baking soda does not directly decrease the chlorine levels of a swimming pool, but aids in the neutralization process of chlorine. One of the high alkaline chemicals is baking soda and adding this to your swimming pool will increase the water's pH and alkalinity. '

What neutralizes chlorine in a pool?

Two different chemical agents that can reduce chlorine levels are Sodium Thiosulfate and Pool-Grade Hydrogen Peroxide (specific to pool treatment). Be sure to test your water after using one of these agents as they tend to impact pH, sometimes dramatically.

Does sunlight reduce chlorine in pool?

That gorgeous sunlight you like to enjoy near the pool also affects the chlorine. The sun's ultraviolet rays can cut down the chlorine concentration by 90% in as little as two hours. And on very hot days, the chlorine will deplete faster, becoming a cesspool for bacteria.

What happens if chlorine is high in a pool?

Too much chlorine in the pool can cause swimmers to feel like their eyes are itching, it can cause discomfort on the skin and it can lead to the fading of your swimsuits.

Does chlorine go away on its own?

Yes, chlorine is a gas and will evaporate. If you leave a glass of water to stand in the open air for up to 24 hours, it will be chlorine free.

Is it okay to swim in a pool with low chlorine?

FALSE. It doesn't matter how much time and effort you put into skimming, brushing, vacuuming, circulating, and filtering your pool. If there's not enough chlorine in the water, your pool's not actually clean, and the water's not safe.

Why does my pool chlorine level drop so quickly?

Sun Exposure (UV Rays): Ultraviolet rays from the sun can break up free chlorine very quickly. Without stabilizers (such as cyanuric acid), chlorine is less effective, and its levels fall more rapidly in outdoor pools.

How fast does chlorine dissipate in a pool?

Natural dechlorination will occur over time and chlorine will dissipate when exposed to the air and sunlight. This process can take 5-10 days, depending on a variety of factors, including pool size.

What filter removes chlorine from water?

Activated carbon filters

They are one of the best ways to purify chlorinated H2O by removing its by-products, chemical taste, and odor. You can either get it as a carbon block or granular activated carbon. Either way, the carbon filters will remove about 99.9% chlorine from your drinking water.

How long does chlorine last in a pool?

Under normal conditions, you should add a chlorine tablet every 3-7 days. However, several factors can influence how often you need to add chlorine: Frequency of use: A heavily used pool will require more frequent chlorination. Sunlight: Sunlight breaks down chlorine, so you'll need to add it more often on sunny days.

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