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No Free Chlorine in Pool After Shocking? Here’s Why

Free chlorine is the chlorine that can be used to sanitize the pool. If your pool doesn’t have any free chlorine, it’ll get cloudy and develop algae blooms.

These dangerous blooms can cause health hazards, expensive repairs, and more. It’s crucial that you find out why your pool shock isn’t improving the free chlorine.

If there’s no free chlorine in the pool after shocking, there’s likely too much algae and bacteria in the water. Algae are neutralized by chlorine, but they convert it into chloramine. The chloramines are ineffective against algae. Remove the algae to restore the free chlorine.

Throughout this post, I’ll discuss why your pool doesn’t have any FAC (free available chlorine) after shocking the water. I’ll also explain how pool shock affects the free chlorine and why it isn’t clearing the swimming pool.

Why Is Your Pool Showing No Free Chlorine After Shocking?

If your pool doesn’t show any free chlorine after shocking it, you’re probably dealing with an algae bloom. Microscopic bacteria neutralize the free chlorine, which turns the chlorine into chloramine. The chloramine is useless because it saturates the water and doesn’t remove the algae from the swimming pool.

Here’s a list of additional reasons your pool doesn’t have free chlorine after a shock treatment:

  • You didn’t add enough shock to the swimming pool. If you don’t use enough liquid or granular chlorine, your pool won’t show enough FAC when you test it. Granular chlorine is much stronger than liquid chlorine, so it’s the better choice for those who need to spike their pool’s chlorine levels.
  • You use low-quality pool shock. In the Swim’s Calcium Hypochlorite is an ultra-potent granular shock that quickly elevates the pool’s free available chlorine. If there’s a lot of algae in the water, this shock will eliminate it and regulate the chorine. One pound of this 50-pound tub is enough to treat 10,000 gallons.
In The Swim Calcium Hypochlorite Chlorine Granular Pool Shock – 50 Pounds
  • There are a lot of total dissolved solids in the water. Too many total dissolved solids prevent your pool water from absorbing anything else. The chlorine will puddle in one area of the liner and damage it. You’ll have to drain a couple of feet of water if the TDS is above 2,000ppm.
  • There are too many chloramines in the pool. Chloramines make chlorine inactive. You can use a chlorine neutralizer to remove the chloramines and restore the free available chlorine. Use In the Swim’s Water Chlorine Neutralizer to lower the TAC and equalize the FAC. One of the 2.25-pound containers is enough for several seasons.
In The Swim Pool Water Chlorine Neutralizer – 2.25 lb

As you can see, there are many reasons why your pool might not have enough free chlorine. You might also have to replace the drops or test strips if they’re expired. Old, worn strips and drops can provide false readings, making you think there’s less chlorine than there is.

Does Shock Affect Free Chlorine?

Shock affects free chlorine by elevating the FAC and TAC in the pool. Granular shock is the most effective variant, but liquid pool shock can increase the free chlorine, too. Not using enough shock can have adverse effects, as can using too much chlorine. Never let the chlorine get below 2ppm or above 5ppm.

Many experts recommend shocking the pool weekly or bi-weekly, depending on the season, climate, and sanitizer. Failure to shock the pool often enough will prevent the free chlorine from staying at the proper levels. Furthermore, you’ll end up with a lot of dead algae and cloudy water since there’s not enough to kill the whole bloom.

It’s also a good idea to shock your pool after parties, heavy swimming, long rainstorms, and whenever your pet swims in the water for longer than an hour. All of these activities add contaminants known to encourage algae growth. Shocking the pool will prevent algae from growing and keep your pool clear.

Here’s what you should know before shocking your pool to adjust the free chlorine:

  • Test the free available chlorine and the total available chlorine before adding shock (or any other chlorine) to the pool.
  • Some shocks balance and rejuvenate the chloramines, turning them back into free chlorine.
  • All shocks have different chlorine levels that could spike the chlorine much more than others.
  • Some shocks are designed to evaporate quicker than others in case you have a pool party around the corner.

Using shock is an essential part of owning a swimming pool (even if you have a saltwater pool). However, it’s crucial that you use the right quality, quantity, and type of shock for the water. If you’re concerned about cloudy water after adding a shock treatment, read on.

Why Does My Pool Not Clear After Shocking?

Your pool doesn’t clear after shocking the water because you added too much shock, the water hasn’t circulated enough, or there’s a dead algae bloom in the water. Dead algae is cloudy, so it needs to be removed via filtration. You can expedite the process by adding a water clarifier to increase the filter’s micron density.

Removing the dead algae will get rid of the cloudiness. Use Robarb’s Super Blue Clarifier to get rid of the cloudiness in the pool. This chemical binds to the filter and makes it much more effective. Add the clarifier, run the pump for at least six hours, then clean the filter to remove the dead algae.

Robarb Super Blue Clarifier (1 Quart)

Keep in mind that your filter’s PSI will likely get much higher when you use a clarifier. It intentionally clogs the filter with the thick ingredient to catch the fine debris and dead algae. The result is a much clearer pool in less than a day.

Pool owners often think the shock will clarify the water, but it can’t remove the dead algae. Clarifiers and constant filtration are the best sources of clarification for your cloudy pool water. However, you can kill the algae with shock and clear it with filtration, making it the best two-part solution. Remember to add the shock evenly around the edges.


  • Jonah Ryan

    Jonah has worked for several years in the swimming pool industry installing and repairing equipment, treating pools with chemicals, and fixing damaged liners. He also has plumbing and electrical experience with air conditioning, ceiling fans, boilers, and more. When he's not writing for Temperature Master, he's usually writing for his own websites, and

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