Pool chemicals can be crazy at times, but high chlorine levels are usually pretty straightforward to deal with. Indoor pools are more complicated, but there are several options. If you want to reduce your current chlorine levels without risking contamination, UV exposure should help.
Steps
Method 1 of 3: Basic Methods
Step 1. Find out what causes chlorine odor and burning eyes
Many people attribute the smell of chemistry or burning eyes to chlorine. But in fact, they arise after the chlorine has broken down into its constituents. Use the shock method to increase chlorine levels. Better yet, take a water sample and measure the exact chlorine level.
Step 2. Take a sample from the pool
If you have not already done so, check your chlorine levels with a special kit from a pool supply store. Make sure the test kit measures both free active chlorine and total chlorine.
- As a rule, the free chlorine content should be in the range of 1-3 ppm. The total chlorine content should not be more than active by more than 0.2 ppm. Your local health and safety code may have different requirements.
- If your pool also uses ozone or UV disinfection, the active chlorine content can be reduced to 0.5 ppm.
Step 3. Remove sources of chlorine
If the chlorine level has increased only a tiny bit (somewhere around 4-5 ppm), the use of chemicals is not required. Just stop adding chlorine to the pool, and then the problem will most likely resolve on its own.
To stop adding chlorine, turn off the chlorinator, chlorine corrector or salt water cleaning system, remove the chlorine tablet from the skimmer, or remove the chlorine dispenser. If you are unsure which system you have in your pool, ask the manager or owner
Step 4. Remove the cover from the outdoor pool
Ultraviolet light from the sun quickly breaks down chlorine molecules. One cloudless day can remove up to 90% of the chlorine from your pool, if, of course, you remove all sources of chlorine from it.
UV lamps are not the best replacement for this step. Check out the UV method below for more information
Step 5. Swim until the chlorine level is at a safe level
Swimming can help lower chlorine levels, but this should only be done if the chlorine reading is only slightly overestimated (4 ppm). Experts disagree about what chlorine levels are harmful to swimmers. Public pools usually close at 10ppm, while other pools close at 5ppm for added safety.
- Do not swim if your pool water analysis shows additional unexpected results, such as unsafe pH or alkalinity.
- Do not swim if you smell strong chlorine (and the water sample showed a high chlorine content). This smell is actually caused by irritants called chloramines.
- Chlorine affects the lungs. It is more dangerous in poorly ventilated areas and for people with breathing problems.
Step 6. Replace some of the pool water
This is an expensive and slow method, but it can dilute the chlorine content. Drain and replace in the pool with about 1 / 3-1 / 2 of the water. After changing the water, it can take a long time for the pool to return to normal chlorine and pH levels.
The quickest way to (partially) drain the pool water is to use a filter with the backwash option
Step 7. Take a water sample regularly
Take a pool water sample once or twice a day, or every couple of hours if the pool is in use. If the chlorine level does not decrease within a few days, try one of the following methods.
The Tips section provides advice on other sample results such as pH and cyanuric acid levels. If your test results fall outside these guidelines and do not improve soon, you may need to hire a professional
Method 2 of 3: Using Chemicals to Reduce Chlorine Levels
Step 1. Buy a chlorine neutralizer from a pool supply store
Ask the seller for advice if you are unsure of which to choose. Do not use chemicals from other sources. The chemicals in these stores have a special concentration specifically designed for swimming pools.
- Sodium thiosulfate is probably the most popular chlorine neutralizer, but requires careful handling.
- The cheapest option is hydrogen peroxide, which breaks down into harmless substances. However, it is less effective if the pool pH is below 7.0.
Step 2. Close the pool
Never add chemicals to the pool while someone is in the pool. If other people have access to the pool, then you should post clear warning signs.
Step 3. Follow the precautions
Many pool chemicals may cause some damage on contact with the lungs, eyes, or skin. Please review this list of precautions before proceeding:
- Read the instructions for use on the label carefully. Follow all recommendations for use and read the course of action in case of an emergency.
- Store pool chemicals in a well-ventilated area, away from sunlight, heat, and moisture. Do not store acids and chlorine next to each other. Do not store dry chemicals near or under containers of liquid.
- Keep only one chemical container open at a time. Close and replace the first container before opening the second container.
Step 4. Calculate how much chemical you need
Always follow label directions to determine how and how much to add to your pool. Many chemicals are available in various forms and concentrations, so a general guideline cannot cover all possible cases.
- Typically, the rate of sodium thiosulfate is about 15 ml per 3800 liters of water.
- If you are handling a public pool, use more accurate measurements. 77 ml of sodium thiosulfate will reduce the chlorine level by 1 ppm in 37,900 liters of water. A store clerk or an online chlorine reduction calculator can help you with these calculations.
Step 5. Add neutralizer in small doses
An excessive amount of neutralizer can cause serious problems: the chlorine level can drop to zero, and unused neutralizer will remain in the pool to destroy the next batch of chlorine. Take 1/3 or 1/2 of the calculated amount.
Step 6. While you wait, periodically take a robe of water
Wait as long as indicated on the instructions on the label with the substance. Test often and stay out of the pool until the water reading returns to normal. If the reading stabilizes but the chlorine content remains too high, add another small dose of neutralizer.
If the pool has a slow circulation system, you will have to wait longer for the neutralizer to work
Step 7. Raise the pH level if necessary
These chemicals tend to lower the pH level in the pool. Be prepared to raise the pH level when the chlorine level returns to normal. The pH level should be between 7, 2 and 7, 8, and ideally as close to 7, 5 as possible.
Method 3 of 3: Using UV lamps
Step 1. UV disinfection
Ultraviolet (UV) pool lamps can neutralize most germs, but alone they cannot keep the pool safe. However, they are able to reduce the amount of free chlorine to as much as 1 ppm, and sometimes even lower. They can also decompose some of the irritating and harmful substances that appear in the chlorinated pool. Finally, although they are rarely used for this, some types of lamps are capable of breaking down high levels of chlorine.
Local health and safety codes may have different requirements for their implementation
Step 2. Medium pressure UV lamps
Such a lamp is universal and the following advantages:
- It is the only lamp freely available that is capable of decomposing significant amounts of chlorine. But even in this case, you will need a dose 10-20 times more than recommended for disinfection. You will probably need to take several lamps for this.
- It is the most effective lamp for breaking down chloramine, a substance responsible for burning eyes, irritated skin and chlorine odor.
- While this lamp is relatively good for disinfection, it is not recommended to use it.
Step 3. Consider using a low pressure UV lamp
This type of lamp, often referred to as a purifier, has excellent disinfectant performance, although you will still need to use a reduced amount of chlorine. This makes it a good option for public swimming pools.
- These lamps are also cheaper and more durable than medium pressure lamps.
- The description may say that these lamps remove chloramine. This is partly true, but in practice they may not diminish visible signs such as burning eyes.
Step 4. Consider other options
There are also other types of UV lamps, although they are less common. Here's some information to help you determine the effect of each:
- "Ultraviolet" actually includes a wide variety of light with different effects. It is generally classified as UV-A (315-400 nm), UV-B (280-315 nm), and UV-C (100-280 nm). The description of each fixture must indicate either the type of light or the wavelength range (eg 245 ni).
- Only UV-C light has the ability to disinfect swimming pools.
- Only UV-A light (including UV light from the sun) decomposes a significant amount of chlorine. But this will require a fairly intense amount of light.
- All three types break down chloramine.
Step 5. Check the pool after installation
We recommend that you hire a specialist to install the UV system. If you set everything up properly, system maintenance will be kept to a minimum. Continue testing your pool water for chlorine at 1ppm or less as recommended by your pool or local regulations.
Advice
- Pool chemicals degrade over time. For best results, do not buy more than you intend to use in one season.
- If you smell chlorine, know that it actually smells like its byproduct, chloramine. This is usually a sign that more chlorine needs to be added to make the pool safer. Shock therapy is common in home swimming pools.
- If you need to quickly disinfect a pool, increase the chlorine level and then chemically lower it.
Warnings
- If you are still getting unexpected data, check the other sample results. For a stable chlorine level, the pH should be between 7, 2 and 7, 8, the alkalinity between 80 and 120 ppm (depending on the type of chlorine), and the cyanuric acid content between 30 and 50 ppm. Your local health and safety code may have slightly different standards.
- In some regions, test results may include a substance called "orthotolidine" that causes cancer. Wear gloves when collecting the sample and do not throw it back into the pool. Note that these tests only measure total chlorine, not free chlorine that can be disinfected.