Sometimes being able to manage pool water properly can be frustrating, but lowering too much chlorine is usually very simple. Indoor swimming pools are considerably more difficult to manage, but even in this case there are many solutions available. If you prefer to monitor the chlorine level on a daily basis, the ideal choice is to install a system with UV lamps.
Steps
Method 1 of 3: Basic Techniques
Step 1. Understand the causes of the "smell of chlorine" and the classic burning in the eyes when you are near or in the water of a swimming pool
Many think that the smell of chlorine in the air or the stinging of the eyes after swimming is linked to a high level of chlorine in the water. In fact, these phenomena occur when chlorine degrades into other chemical by-products. The correct solution in these cases is to raise the level of chlorine present in the water through a so-called "shock chlorination" or "shock chlorination". water and take an accurate reading of the chlorine level. All the necessary steps are described in detail in the next point.
Step 2. Use a pool kit
If you have not already done so, check the chlorine levels in the pool water using a special kit. You can easily find it in any specialized shop or online. Make sure the kit can measure both free and total chlorine levels.
- As a generally adopted rule, the free chlorine level should be between 1 and 3 ppm. The total chlorine level, on the other hand, should not be more than 0.2 ppm higher than the free chlorine level. The standard levels adopted by health institutions in the area you live in may be slightly different.
- If your pool uses an ozone-based disinfection system or UV lamps, the free chlorine level can be reduced by 0.5 ppm.
Step 3. Remove the chlorine sources
If the chlorine level is only slightly above normal (around 4-5 ppm), using chemicals to lower it quickly is usually not necessary. Simply stop adding chlorine to your pool water, the problem will most likely resolve itself in no time.
To stop adding chlorine, turn off the automatic chlorine system, remove the controlled release chlorine dispenser from the water, turn off the salt chlorinator or remove the chlorine tablets from the pool skimmers. If you are not sure which chlorination system is used for the pool in question, ask the maintenance manager or the owner directly
Step 4. If it's an outdoor pool, don't cover it
The ultraviolet rays of the sun will very quickly degrade the chlorine present in the water. A single afternoon sun exposure is able to remove 90% of the chlorine present in the water of an outdoor swimming pool, provided that any automatic chlorination system has been removed or blocked.
Normally, adopting a UV lamp system is not a good solution for this problem. For more details, please refer to this section of the article
Step 5. Use the pool when the chlorine levels are normal
Swimming helps reduce the chlorine level in the water, but you can only use this method if the chlorine level is slightly higher than ideal (no more than 4 ppm). Experts disagree in defining which chlorine levels are dangerous for the health of swimmers. Public swimming pools are often closed when the chlorine level reaches a value of 10 ppm, while others adopt a more restrictive limit of 5 ppm.
- Do not use the pool if the tests have also given unexpected results for other factors, such as pH or alkalinity.
- Do not enter the water if you smell a strong chlorine smell in the air (and the chlorine level test gave high values). The smell you smell is caused by the release of irritating substances called chloramines.
- Chlorine affects lung health. It is much more dangerous in areas where it stagnates due to poor ventilation or if bathers have breathing problems.
Step 6. Replace a portion of the water in the pool
This is a slow and very expensive solution, but it is still good for diluting the current amount of chlorine. Drain a quantity of water that varies between ⅓ and ½ of what is currently in the pool, then replace it with fresh water. After this treatment, it may take a long time to restore the correct chlorine and pH levels in the pool.
If your pool is equipped with it, a sand filtration system with the possibility of backwashing is the simplest option to partially drain the water present
Step 7. Perform water checks regularly
Repeat the pool water quality tests once or twice a day or every 2 hours if it is a very busy pool. If your chlorine levels don't drop within a couple of days, try one of the next methods outlined in this article.
See the "Tips" section, it contains guidelines to follow to perform other tests, such as that of pH or cyanuric acid. If your results are outside the ranges provided and you are unable to stabilize them quickly, you may need to seek professional help
Method 2 of 3: Use Chemicals to Lower the Chlorine Level
Step 1. Purchase a chlorine neutralizer at a specialty store
If you're not sure which product is best to buy, ask the store staff for help. Do not look for your chemicals elsewhere, the chemical solutions for swimming pool water must be bought exclusively in specialized stores, in concentrations specially designed for this purpose.
- Sodium thiosulfate is probably the most commonly used chlorine neutralizer, but it requires great care in handling.
- Hydrogen peroxide is often the cheapest solution, and it breaks down chlorine into by-products that are absolutely harmless to health. However, if the pH of the pool is below 7, its effectiveness is greatly reduced.
Step 2. Close access to the pool
Do not add any type of chemical product while the pool is used by bathers. In case other people have access to the area, report the use of chemical agents with clearly visible and clear signs.
Step 3. Comply with all safety regulations
Many pool treatment chemicals can be harmful and irritating if they come into contact with eyes and skin or are accidentally inhaled. Always review the following instructions before proceeding further:
- Read the instructions on the product label. Always carefully follow all the advice regarding the safety measures to be adopted in order to handle the product in peace. Also consult the emergency procedures to be ready to handle any eventuality.
- Store pool treatment chemicals in a well-ventilated area, out of direct sunlight, heat, and humidity. Do not store acids and chlorine in the same place, also never store chemicals in dry form close to those in liquid form.
- Always open only one container at a time. Before opening a second one, close the first one and put it back in its place.
Step 4. Calculate the quantities you need
Always follow the instructions for use on the product to determine the amount to add to the pool water. Many chemicals are available in different forms and concentrations, so it is best to always follow the relative methods of use; this guide does not cover all available options.
- Normally, when sodium thiosulfate is used, an amount equal to 15 ml per 3,800 liters of water is calculated.
- If you have to manage a public swimming pool, take a very accurate measurement, remembering that 77 ml of sodium thiosulfate lower the chlorine level of 37,900 liters of water by 1 ppm. You can get help in the interpretation of this formula and in calculating the quantity of product suitable for your specific case by contacting the staff of a specialized shop or by using one of the many calculators on the web.
Step 5. Add small doses of neutralizer
By using an excessive amount of product, you can worsen the situation instead of solving the problem: the chlorine level could drop to zero and there could be some neutralizer still active in the water that would also destroy the chlorine that you are going to add later. Start by using ⅓ or ½ of the amount you calculated.
Step 6. Perform repeated water quality tests
Wait the required time (normally specified on the label) for the product to take effect. In the meantime, take your chlorine level measurements frequently and do not allow anyone to use the pool until the values have normalized. If the measured values have stabilized, but the chlorine level is still too high, add another small dose of neutralizer.
If your pool water recirculation system is less powerful than average, you may have to wait longer for the neutralizer to do its job
Step 7. If necessary, raise the pH value
The use of these chemicals normally tends to lower the pH value of the water, so be prepared to restore it to ideal levels once the chlorine value in the pool has normalized. The pH should always be between 7, 2 and 7, 8 and, in an ideal situation, it should be as close to 7.5 as possible.
Method 3 of 3: Use Ultraviolet Lamps
Step 1. Understand how ultraviolet disinfection works
UV lamps designed for swimming pool water treatment are able to neutralize most of the germs present. However, they are not enough to perfectly sanitize a swimming pool, but they allow to keep the level of free chlorine below the values recommended by health institutions. They are also able to dissolve the irritating and health-threatening chemicals that are created with the normal use of swimming pool chlorine. Finally, even if they are not used for this purpose, some types of lamps are able to neutralize chlorine when it is present in high concentrations.
Local laws governing the water treatment of a swimming pool may have different requirements for the use of these tools
Step 2. Try using a medium pressure UV lamp
It is a very versatile tool, which offers several benefits:
- It is the only commonly available lamp capable of breaking down a significant amount of the chlorine existing in the water. Nevertheless you will need a disinfection capacity 10-20 times greater than that recommended; for this reason, you will most likely have to adopt a multiple lamp system.
- This is the most effective type of lamp in the elimination of chloramines: the substances responsible for skin irritation, burning of the eyes and the smell of chlorine perceptible near the pool.
- These types of lamps are a good enough option for managing pool water disinfection, but not the best.
Step 3. Consider using a low pressure UV lamp
This type of lamps have excellent water sterilization capacity, but will still need to be paired with regular pool chlorination (although less chlorine will likely be required than normal). This makes them a great option for water treatment of a public swimming pool.
- These types of lamps tend to be cheaper and longer lasting than medium pressure ones.
- The manufacturers of these lamps claim that they are able to eliminate chloramines. This is a partially true statement because in reality they are not really always able to eliminate the classic signs of the presence of chloramines, such as burning eyes.
Step 4. Evaluate other lamp models
Although less common, there are other types of UV lamps. Here is some useful information to understand the differences between the various models:
- The term "ultraviolet rays" refers to a broad spectrum of light whose rays have different effects. The ultraviolet spectrum is normally divided into UV-A rays (315-400 nm), UV-B rays (280-315 nm) and UV-C rays (100-280 nm). You should be able to find lamps that emit ultraviolet light at any wavelength (e.g. 245nm).
- Only UV-C rays are able to sterilize water.
- Only UV-A rays (including ultraviolet rays emitted by the sun) are capable of eliminating significant quantities of chlorine. Even in this case, however, a large lighting capacity is required.
- All three types of UV rays help eliminate chloramines.
Step 5. After installing this tool, run your water quality checks
To install an ultraviolet water treatment system, it is always best to turn to professionals in the sector. Once the system is calibrated to specifications, the required maintenance is very minimal. Continue to check the chlorine levels in the water as you normally would. Check that this value is equal to or less than 1 ppm, in accordance with the levels recommended by the health institutions of the area where you live.
Advice
- The chemicals used to treat swimming pool water degrade over time and lose their effectiveness. For best results, don't buy more than you plan to use in a single year.
- When near a swimming pool you think you can smell chlorine in the air, what you actually smell is the smell of a by-product called "chloramines". This is a clear sign that more chlorine needs to be added to make the pool water safe. The solution normally adopted for private pools consists in carrying out what is called "shock chlorination" or "shock chlorination".
- If you need to quickly disinfect a swimming pool, proceed by greatly increasing the chlorine level in the water ("shock chlorination") and then bring it back to normal levels using special chemicals.
Warnings
- If you continue to get unexpected results when checking your pool water levels, change your assessment tools. To have a stable chlorine level, the pH of the water should be between 7, 2 and 7, 8, the alkalinity between 80 and 120 ppm (depending on the type of chlorine used) while the cyanuric acid between 30 and 50 ppm. Healthcare institutions in the area where you reside may adopt slightly different standard levels.
- In some areas, swimming pool water quality tests also include checking the levels of a substance called orthotolidine, which is linked to the risk of getting cancer. When using this type of test, always wear a pair of protective gloves and, when finished, do not throw the tested water sample back into the pool. Remember that these controls simply measure the total chlorine level, not the "free" chlorine level currently available for water disinfection.
