High chlorine levels in a swimming pool can cause skin and eye irritation, sickness, burns, and many other problems. Chlorine can also deteriorate vinyl, gunite, and fiberglass. If your pool’s chlorine levels stay above 6ppm (parts-per-million) for too long, it’s time to figure out how you can lower them.
To lower the chlorine levels in your pool, follow these steps:
- Test the chloramines
- Remove all chlorinators
- Remove the cover
- Add water
- Consider rainwater
- Heat the pool
- Let people and pets swim
- Use a neutralizing agent
- Try sodium thiosulfate
- Add vitamin C
- Drain and refill the pool
In this article, I’ll show you everything you need to know about lowering your swimming pool’s chlorine levels.
I’ll also explain why they can’t be too high, which steps are required, and whether or not you need to drain and fill the water for extremely high chlorine levels. Let’s get started!
Test for Chloramines
The first step is to test for chloramines to know which kind of chlorine needs to be removed from the swimming pool. Chloramines are the leftover particles from unused chlorine. Your pool’s chlorine is measured with two metrics:
- FAC (free available chlorine): This type of chlorine is the usable, fresh chlorine that hasn’t encountered algae and other contaminants.
- TAC (total available chlorine): This type of chlorine is the free available chlorine combined with the chloramines.
The FAC is the only type of chlorine that should be in the water. Your pool’s TAC and FAC should be as close as possible to each other (preferably between 2ppm to 4ppm or 5ppm to 6ppm if you’re fighting an algae bloom). Too many chloramines cause all sorts of issues, including:
- Chlorine odors drifting from the water
- Itchiness and skin irritation
- Algae blooms (the TAC is often misinterpreted as FAC, so people think they have enough chlorine when they actually don’t)
- An inability to absorb FAC in the water
The best way to avoid these issues is to know how often to shock your pool. Adding too many tablets or liquid chlorine can also contribute to high TAC and chloramines.
Testing for chloramines requires a chlorine test kit. You can choose the dipsticks or the liquid test kits. I prefer the liquid kits because they’re much more accurate, and the liquid kits have a much longer shelf life.
The Taylor Drop Test Kit lets you see how much free chlorine and total chlorine (also known as combined chlorine) are in the water.
The first drops show the free chlorine, and the second bottle shows the total chlorine. These kits come with enough drops to last several seasons. Taylor is a well-known and trusted brand that I’ve used for several years.
Remove Floating Chlorinators from the Water
Your pool likely has chlorine floaters, in-line or off-line chlorine dispensers, or some other form of chlorine dispensing.
Here’s the process I suggest:
- Close the plumbing valves going to all in-line and off-line chlorinators. These chlorinators hold stacks of chlorine tablets, while some of them test and dispense liquid chlorine as needed. However, malfunctioning chlorine dispensers can add too much chlorine, skyrocketing the water to dangerously high levels.
- Remove your chlorine tablet floater. These floaters hold up to six chlorine tablets that add tons of chlorine into the water. People often use too many tablets, which is why chlorine can get too high. Make sure your chlorinator only holds one tablet per 5,000 to 10,000 gallons of water, depending on the brand’s recommendation.
- Don’t dump any powder or liquid chlorine into the water until the chlorine levels are reduced. Also known as liquid shock and powder shock, these types of chlorine can send your pool’s water through the roof with chlorine. Don’t use them until the water dips around 2ppm to 3ppm.
Removing the chlorinators from the pool is one of the most important steps that pool owners often overlook. Make sure you’re using the correct amount of chlorine to prevent the levels from getting too high.
Once you’ve removed the chlorinators, head to the next step to finding out why your pool cover might be the reason the chlorine is too high.
Take the Cover Off of the Pool
Pools often use winter covers and solar covers. Winter covers are ideal for the colder months when you don’t intend to use the pool. Solar covers are great for increasing the pool’s temperature.
Both of these covers work to reduce algae and debris, but they also prevent chemical evaporation.
The good news is that you can use the evaporation element to your advantage. Follow the suggestions below for the quickest results.
- Remove the pool cover during the warmest parts of the day under direct sunlight. The sun’s evaporative properties remove loads of chlorine from the pool. People often struggle to maintain the pool’s chlorine levels without a solar cover. Take off the cover, and you’ll be surprised by how quickly the chlorine dips.
- Spray the solar cover or winter cover to remove dried chlorine. The chlorine can bake onto the cover, causing deterioration. The strong chlorine levels combined with direct sunlight wreak havoc on most pool covers. Some people notice their solar covers crumble if they don’t remove the excess chlorine.
- Circulate the pool pump to promote evaporation. A stagnant pool will cause chemical stains because the chlorine sits in concentrated pockets. Moving the water will evenly distribute the chlorine, helping it evaporate quicker. Furthermore, it prevents algae while the sunlight warms the water.
Unfortunately, evaporation isn’t always the only thing you need to do. If you have a pool party soon or you’re worried about chemical stains and corrosion, it’s time to resort to quicker methods.
Add Hose Water or Well Water
You’ve probably heard the saying, “The solution to pollution is dilution.” This statement couldn’t be more true when it comes to diluting the chlorine in your swimming pool.
Your garden hose or well water doesn’t have very much chlorine. However, it likely has around 1ppm or less, which is worth noting.
Consider these quick tricks for the best results:
- Let the water evaporate from the aforementioned direct sunlight suggestion before filling the water. The goal is to replace as much chlorinated water with fresh hose water or well water as possible.
- Never let the water dip below the highest inlet, which is usually the skimmer basket. Letting the water get too low will cause severe plumbing issues since the equipment will get air bubbles. Trapped air can cavitate the impeller, overheating and damaging the motor.
- Test your water source before adding it to the pool. Some local water sources contain a lot of chlorine and other chemicals. It’s very difficult to reduce your pool’s chlorine levels if the water source has a lot of chlorine. For example, some high-chlorine water sources have as much as 4ppm, which is counterproductive for your efforts.
Pro-tip: Adding well water and hose water to your swimming pool will undoubtedly alter your pool’s chemistry. Most local water sources contain varying alkalinity and pH levels. Some of them also have lots of calcium, total dissolved solids (TDS), and bacteria that could cause algae blooms.
Therefore, you should test and adjust the pool’s chemicals after adding the water.
Store and Use Rainwater
Rainwater offers some of the most effective resources for reducing your pool’s chlorine levels.
This water source almost never contains trace amounts of chlorine since it’s not treated by chemical safety plants. Furthermore, it doesn’t have calcium hardness or TDS that could make your pool harder to manage.
If you live in an area that rains often, you could store the rainwater in a rain collection barrel to dilute the swimming pool’s chlorine.
However, you should remember that this water source can bring with it two problems that you’ll inevitably encounter:
- Rainwater often contains lots of phosphates. Phosphates are algae’s primary food source. The contaminants are found in rain, plants, soil, pet hair, and almost any other natural debris. Make sure the chlorine doesn’t get too low when diluting it, or the phosphates could cause algae blooms.
- Some rainwater is acidic, which means you might have to add soda ash and an alkalinity-increasing agent to the pool. I suggest testing the pool water before altering the chemistry, though. If the rain isn’t too acidic or basic, you might not have to make any pH or alkalinity adjustments.
Make sure you’re allowed to collect the rainwater since not all places allow it. You should contact your city’s officials to know if you’re legally permitted to collect rainwater and use it in your swimming pool.
Fortunately, there are many other ways to dilute and reduce your pool’s chlorine levels.
Heat Your Swimming Pool Quickly
Knowing how to heat your swimming pool can help you quickly evaporate and dilute the chlorine in your pool.
Increasing the water temperature will pull a lot of the water out of the pool. Since chlorine is a gas in its natural state, it evaporates with the pool water. You can use all sorts of methods to heat your pool.
Unfortunately, you shouldn’t use a solar cover to increase the pool’s temperature. I already mentioned that all covers should be removed from the pool during chlorine reduction, so you’ll have to rely on these suggestions:
- Use an electric or gas pool heater. These heaters fit into the plumbing and let you control the pool’s temperature. The Pentair Mastertemp 125K BTU Heater is an excellent choice because it comes with a multi-year warranty, a membrane control board for easy heating, and built-in timers to choose when the heater starts and stops.
- Install a solar heating system. Swimming pools use solar panels to send water through a series of tubes that heat the water. You can also use solar heaters that push the pool water through spiraled tubes for a similar effect. These heating systems require lots of direct sunlight while heating the pool.
I recommend avoiding liquid solar covers and solar rings, though.
While these tools are efficient in terms of chemical retention and evaporation reduction, they prevent chlorine from leaving the pool. It’s best to use them after you’ve lowered and maintained the pool’s chemistry for a couple of weeks.
Let People and Pets Swim
People and pets contain loads of phosphates. Since algae blooms feed on phosphates, it’s understandable that swimming in the pool would use chlorine. Your pool’s chlorine goes away based on the number of algae in the pool, evaporation levels, and dilution.
If you have the cover off of the pool and people are splashing around, you’ll have to use the hose to top off the water levels. This simple activity checks all three boxes required to reduce the pool’s chlorine levels.
However, it’s unsafe to swim in a pool if the chlorine is higher than 6ppm. You should never allow people or pets in the pool if your swimming pool has too much chlorine.
People and pets will have itchy skin, burning sensations, and many other potential health concerns. This method should be a final step for slightly high chlorine levels, but you might have to dilute or neutralize the chlorine with stronger chemicals beforehand.
You might’ve noticed that your pool’s chlorine levels are much lower after a pool party. That’s because everything from dead skin cells to hair and dander uses chlorine.
The chlorine attaches to the contaminant and turns into chloramine, the substance we referred to earlier.
It’s quite common for your pool’s chlorine to drop and the chloramines to increase after heavy swimming. For this reason, people often test their total chlorine (TAC) and assume the chlorine is good to go. A few days later, a massive algae bloom proves otherwise.
Chloramines and high free available chlorine need to be diluted or neutralized. Read on to find one of the most effective chlorine neutralizing suggestions.
Use a Chlorine Neutralizer
Chlorine neutralizers have become some of the most underrated and widely needed chemicals in the pool industry. These chemicals reduce the free available chlorine and chloramines, returning your pool to its original condition.
Cutting the chlorine and chloramine is a crucial part of owning and maintaining a swimming pool.
BioGuard Chem Out reduces the chlorine and bromine in your pool or spa. Having too much of either chemical in the water will make it dangerous to use.
One two-pound bottle has enough neutralizing power to fix most pools’ and all spas’ chlorine and bromine problems. Dump the solution into the skimmer and circulate the pump with the cover off for the quickest results.
Keep these things in mind when using a chlorine neutralizer:
- Using too much chlorine neutralizer can remove all of the chlorine in your pool. You shouldn’t get rid of all of the chorine, or your pool will get filled with algae. I highly suggest reviewing the chemical’s instructions to know how much you’re supposed to use for your size swimming pool.
- Not all chlorine neutralizers get rid of chloramines. If your pool has a lot of TAC and low FAC, you should make sure the neutralizer handles chloramines. Unbalanced FAC and TAC levels can cause algae blooms and render your pool’s chlorine ineffective. Furthermore, it can make your pool smell like bleach.
- Almost all chlorine neutralizers make your pool look cloudy for a short time. The dense granules cause this issue, but it gradually goes away. Circulate the pump the whole time you use the chlorine neutralizer to get rid of the cloudiness. Test the chlorine after a couple of days, then repeat the process if needed.
Consider Sodium Thiosulfate
Sodium thiosulfate is becoming increasingly popular for reducing chlorine levels in swimming pools.
I recommend using sodium thiosulfate as a safer alternative to most harsh chemicals used to reduce chlorine in the water.
While it wasn’t accepted at first, this chemical is now one of the best treatments to lower the chloramines and balance the TAC.
In The Swim Chlorine Neutralizer uses 90% granular sodium thiosulfate to remove the chlorine and chloramines from your swimming pool. Five ounces of this chemical treats 10,000 gallons of water to drastically reduce the chlorine by up to 5.5ppm. You’ll receive 2.25 pounds per bottle, so it can be used for several swimming seasons.
There are three things you should know before treating your pool with sodium thiosulfate:
- Combining this chemical with chlorine creates an inactive salt, which will increase your pool’s salinity and total dissolved solids.
- You shouldn’t use sodium thiosulfate if your pool has too much salt since it makes it difficult for other chemicals to dissolve.
- Much like all other chlorine neutralizers, sodium thiosulfate will likely cause cloudiness that eventually goes away.
Sodium thiosulfate is an excellent choice for those who don’t want to use harsh chemicals or intense dilution to solve their chlorine problems.
However, there’s another (much more natural) solution you could try.
Add Vitamin C to Neutralize the Chlorine
The United States Department of Agriculture states that you can use ascorbic acid (vitamin C) to reduce your pool’s chlorine and chloramine levels.
Vitamin C has become a hot choice for those who prefer safe, effective treatments for high chlorine levels. It can be used in swimming pools, drinking water, spas, gray water tanks, and more.
People often use vitamin C for high chlorine levels because it’s safe to use around people and pets. It oxidizes chlorine and promotes chemical evaporation.
For this reason, it’s not recommended to use as a routine treatment. Only use vitamin C if you have too much chlorine in the pool, not to manage algae blooms or cloudiness.
Another reason people use vitamin C is to create an at-home spray to remove chlorine after swimming.
It’s important to remove the residual chlorine (and other chemicals) by showering or spraying them off. Mix the ascorbic acid with water, then spray it on your skin to neutralize and remove the excess dried chlorine.
Here’s what you need to know beforehand:
- Use 2.5 parts of ascorbic acid per one part of water. It’s important to use these measurements to prevent your skin from itching from the excessive amounts of acidity found in the ascorbic acid. Furthermore, this solution will quickly dissolve in the swimming pool since it’s already mixed.
- Ascorbic acid has a slightly low pH and alkalinity. You might have to add an alkalinity increase and soda ash to regulate these levels. However, make sure you test them beforehand. Vitamin C might actually balance the pH and alkalinity if they’re too high from the chlorine chemicals.
Drain and Refill the Swimming Pool
Nobody wants to drain and refill their swimming pool if they don’t have to. It’s a long, tedious, and often costly process.
However, I’ve found it to be the most effective way to reduce high chlorine levels, cyanuric acid, total dissolved solids, salinity, and calcium hardness in the water.
To drain and refill the pool, follow these steps:
- Turn off the pool pump and make sure it doesn’t turn on until the water is filled above the skimmer basket.
- Place a sump pump in the water and connect a hose to it.
- Put the other end of the hose wherever you can drain the water.
- Drain the pool ⅓ of the water, then refill it with a garden hose, rainwater, or well water.
Pro-tip: Don’t drain the pool more than ⅓ of the way, or you can risk damaging the liner, gunite, or fiberglass.
Those who need a sump pump to drain their pool should try the Superior Pump’s Submersible Utility Pump.
All you have to do is place the sump pump in the water, connect a hose, plug in the pump, and turn it on. This pump has an auto-shutoff in case water gets into the electrical components. It can remove up to 1,800 gallons of water per hour.
If you prefer a video tutorial, watch this helpful guide to learn how to drain your swimming pool: