How do I fix free chlorine in my pool?

Author: Dr. Kenya Lind  |  Last update: Saturday, August 16, 2025

If your levels are low, start by simply adding more chlorine. Then use test strips or a liquid testing kit to determine the current level. Finally, add chlorine granules to raise the levels quickly. If that doesn't work, shock your pool.

Will shock raise free chlorine?

"Shocking” refers to the process of adding chlorine or non-chlorine pool chemicals to the water in order to raise the "free chlorine” level. The goal is to raise this level to a point where contaminants such as algae, chloramines and bacteria are destroyed.

What can I add to my pool to raise free chlorine?

FC is raised with bleach, trichlor tablets/pucks/sticks, dichlor powder, cal-hypo powder/capsules, or lithium hypochlorite. Only use bleach without any additives, typically labeled unscented or "original scent". Trichlor and dichlor also add CYA and lower PH. Cal-hypo also adds calcium.

What is the fastest way to lower free chlorine?

There are several possible ways to reduce the chlorine levels to acceptable limits quickly.
  1. Stop automatic dispensers. ...
  2. Take a swim. ...
  3. Remove the sun cover. ...
  4. Add some hydrogen peroxide. ...
  5. Dilute the pool. ...
  6. Add sodium thiosulfate. ...
  7. Get help to keep your pool water clean.

Why is my pool showing no free chlorine?

Most likely, the chlorinator is clogged, or the reagents are bleaching out due to high chlorine. Try an OTO chlorine test, as OTO does not bleach out. Caution, if the feeder is clogged, then the feeder could be dangerously full of chlorinated gas. Only open it if you feel that you can do it safely.

Low Chlorine? How to Raise FREE CHLORINE in Your Pool

How to unlock free chlorine in pool?

The fastest and most accepted way to break a chlorine lock is by shocking your pool and achieving breakpoint chlorination. This is done by triple shocking your pool with UNSTABILISED CHLORINE. Don't use stabilised chlorine as the added cyanuric acid will worsen the problem.

Why is my pool not producing chlorine?

Low/No chlorine production

The factors that affect chlorine levels include the summer heat, poor filtration, bather load, and the frequency of use. It's also possible that the time period you set is too short, the chlorine output level is too low, or the filter needs backwashing.

Will baking soda lower free chlorine?

Baking soda doesn't reduce chlorine levels in a hot tub. It increases the pH and alkalinity of the hot tub water or spa water, whichever one. When added to chlorinated water, baking soda increases the pH level so other chemicals can react faster.

What do I do if my free chlorine is low?

The answer here is pretty simple – add more chlorine. If your free chlorine reading is below 1 ppm, your water isn't being sanitised properly, and you'll need to take action. If the levels remain low when adding a dose of your usual chlorine tablets or granules, it's a good idea to shock your pool.

What chemical increases free chlorine?

Raising Free Chlorine with Trichlor

Trichlor, also known as trichloroisocyanuric acid, is especially popular in outdoor pools. Inexpensively priced, this stabilized chlorine is available in various formats such as pucks, sticks, and granules.

Is it OK to swim in a pool with high free chlorine?

Short Summary. It is essential to regulate chlorine levels in a pool between 1-3 ppm, as levels exceeding 5 ppm can be hazardous. Swimming in a pool with high chlorine levels should be avoided. The highest safe chlorine level for a pool is 3 ppm.

Is shock the same as chlorine?

1) What is the difference between chlorine and shock? Do I need to use both? Chlorine is a sanitizer, and (unless you use Baquacil products) is necessary for maintaining a clear and healthy pool. Shock is chlorine, in a high dose, meant to shock your pool and raise the chlorine level quickly.

Why is my chlorine level not going 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.

Why is my pool shocked but no chlorine reading?

If you test your pool water and can't get a chlorine reading at all it may be due to very high chlorine demand. High chlorine demand is the inability to keep an adequate level of chlorine in the pool water even though the water appears to be balanced and properly maintained.

How to raise chlorine level in pool quickly?

Raising pool chlorine can be much easier than trying to lower chlorine levels. Simply adding chlorine in the form of chlorine tablets, granular chlorine, liquid shock or powder shock will increase the total amount of chlorine within the pool.

What is more important, free chlorine or total chlorine?

Free chlorine is the most important parameter to measure when ensuring water is safe for human consumption, while total chlorine is important to measure when monitoring the effectiveness of chlorine disinfection and its impact on the environment.

What can I add to increase free chlorine?

Cal-hypo is the strongest type of chlorine shock available and will help quickly raise your free chlorine levels. Because cal-hypo shock is unstabilized chlorine, you'll need to add it to your pool at night to avoid the sun's UV rays destroying your shock. Then wait at least 8 hours before swimming again.

What does free chlorine mean on a test strip?

Free chlorine refers to the amount of chlorine that has yet to combine with chlorinated water to effectively sanitize contaminants, which means that this chlorine is free to get rid of harmful microorganisms in the water of your swimming pool.

What does baking soda do for a pool?

Baking soda, also known as sodium bicarbonate is naturally alkaline, with a pH of 8. When you add baking soda to your pool water, you will raise both the pH and the alkalinity, improving stability and clarity. Many commercial pool products for raising alkalinity utilize baking soda as their main active ingredient.

What to do if free chlorine is very high?

Tips to Lower the Chlorine Level in Your Pool
  1. Stop Adding Chlorine and Start Swimming. ...
  2. Use the Sunshine. ...
  3. Heat the Pool Water. ...
  4. Dilute the Pool. ...
  5. Use Hydrogen Peroxide. ...
  6. Use a Chlorine Neutralizing Product. ...
  7. Try Sodium Thiosulfate.

How do you neutralize free 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 algaecide lower chlorine levels?

“The algaecide will [deplete the existing] chlorine level dramatically, so you're going to have to add chlorine on top of it in order to activate the algaecide and to best utilize it in the pool,” Wilbur says. Preventing algae growth is more cost effective than having to treat an algae problem.

How do I fix no free chlorine in my pool?

  1. Shock Your Pool: The best way to solve low free chlorine levels is through shock treatment. ...
  2. Check and Adjust pH Levels: Now, you must test the pH before you add more chlorine. ...
  3. Use a Chlorine Stabilizer: Adding a stabilizer such as cyanuric acid will prevent the sun from burning through your free chlorine.

How do I add chlorine to my pool fast?

Using a pool chlorine floater is a common, easy way to apply tablet chlorine to a pool. Make sure the floater is designed for the type of chlorine you're using and the tablet size, either 3 inches or 1 inch. Simply drop the required number of tablets in the floater and put the floater in the pool.

What eats chlorine in a pool?

Bacteria, algae and microscopic contaminants, such as urine, sweat, sunscreen and beauty products, take a toll on your swimming pool's water chemistry. These substances, when present in your pool water, accelerate chlorine demand and can affect your chlorine's ability to maintain properly sanitized water.

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