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How to Reduce Pool or Spa Chlorine Levels

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If you’re a pool service technician, then you know the importance of keeping chlorine levels in check. Reducing chlorine levels is probably something you do on a daily basis as you are well aware of its adverse effects.

Too much chlorine can be harmful to swimmers and can also corrode your pool or spa equipment. Thankfully, there are a few things you can do to make this process a little bit easier. In this blog post, we’ll discuss some of the best ways to reduce chlorine levels in pools or spa without sacrificing safety or performance.

Reduce pool chlorine

There are several ways to reduce the chlorine level in a swimming pool; here are the top 7 methods that are followed religiously for reducing the chlorine levels:

Test the water first

Testing a pool’s water will give you up-to-date results on the current chlorine levels. Based on the results you can determine if adjusting chemical levels is necessary.

According to the CDC (Centre for Disease Control and Prevention), the chlorine level in your pool should be one ppm (parts per minute), and for hot tubs, three ppm; readings outside this range indicate an inhospitable swimming environment and any reading above this is not a safe place to swim.

Tip: Use a liquid testing kit to determine chlorine levels as these will give more precise results than those offered by testing strips.

Suggest the natural approach

It is possible to reduce chlorine levels in a pool without the use of chemicals. Assuming the chlorine levels are not alarmingly high, you can simply ask customers to leave their pool uncovered for a few days—exposure to UV light should bring the levels down naturally. This will not work in all cases, of course. Sometimes chemical intervention may be necessary. But in mild cases, your customers may like having a more natural option that does not involve adding more chemicals to the pool.

Tip: Do not use this method if the pool is preloaded with cyanuric acid—as it acts as a chlorine stabilizer.

Add fresh water to the pool

By refilling at least 20 percent of the pool with fresh water you will be effectively diluting chemicals present and bringing chlorine levels down. Again, this is an excellent option if you have a customer who is reluctant to use more chemicals than necessary to balance chlorine levels in their pool.

Using this technique is advised only if dealing with chlorine levels 1–2 ppm higher than the target range. As you are adding large quantities of fresh water to the pool it will also have the effect of diluting other chemicals present as well, not just the chlorine. Additional precautions and thorough testing of your pool water are required when implementing this method.

Tip: Using the backwashing method with sand and DE filters, if available, saves more time.

Heat the pool water

If you want to reduce the chlorine level in your pool, you can try heating the water. This will cause the chlorine to evaporate, leaving your customers with cleaner water to swim in. Heating the pool to 90 degrees Fahrenheit will reduce the chlorine level in the water.

This is because the chlorine evaporates faster at higher temperatures. By raising the temperature, you’re essentially making the pool less chlorinated.

Tip: Keep temperate within 90–100 degrees Fahrenheit for a short period.

Mix some hydrogen peroxide into the pool water

Hydrogen peroxide, used for cleaning your wounds, can act as a suitable reagent for chlorine reduction. Use food-grade hydrogen peroxide at a concentration of 35 percent.

Start with adding smaller amounts to the pool water, adding larger quantities as necessary. For the hydrogen peroxide to work expect that six or seven hours will be required.

Tip: The shelf-life of this product is low, so don’t stock it in your truck and buy the product only when you need it.

Use chlorine neutralizing agents

If you are a little pressed for time, use chlorine neutralizers. Chlorine neutralizing agents are chemicals that are used to remove chlorine from water. These chemicals are designed to break down chloramines, which are compounds that form when chlorine reacts with ammonia. Some common chlorine neutralizing agents include sodium thiosulfate and ascorbic acid.

Tip: Liquid chlorine can be neutralized with soda ash, also known as sodium carbonate. You can also use hydrated lime, which is calcium hydroxide.

Use ascorbic acid

Chlorine levels in pool water can be reduced by using ascorbic acid. Ascorbic acid is a natural antioxidant that can help to neutralize chlorine. The ascorbic acid reacts with the chlorine—reducing the amount of free chlorine in the water. This can be a helpful way to reduce the amount of chlorine in the pool water quickly without any hazardous side effects.

Tip: You will need to use a higher quantity than chlorine neutralizers to get better results.


Reducing chlorine levels is something that all pool service technicians should be well-versed in. It’s important to keep chlorine levels in check, as too much chlorine can be harmful. So, don’t forget to add this step to your pool service checklist.

In this blog post, we’ve discussed some of the best ways to reduce chlorine levels without sacrificing safety or performance. Keep an eye on our pool cleaning blogs for more tips and tricks on keeping your pool clean and chlorination under control!

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