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News Dry Ice in Pools: Recipe for Problems

Why Not to Use Dry Ice in the Pool

We’ve all seen movies or tv shows where people use dry ice to create a spooky white fog that creeps along the ground. Perfect for Halloween, right? You might be thinking that for your Halloween patio party, instead of a smallish bucket of water, why not dump dry ice in the swimming pool and make massive amounts of thick ground fog to really creep up your event?

That may sound cool (and smart), but it’s actually a really bad idea that will disturb your pool water chemistry and possibly even damage the pool itself — not to mention the health risks to yourself, family, and friends.

What is Dry Ice?

Dry ice is solid carbon dioxide — carbon dioxide gas that has been pressurized and cooled at -109 degrees Fahrenheit (-78 degrees Celsius) to form a solid. Because carbon dioxide (CO2)is a gas at room temperature, it doesn’t melt like “wet ice” but instead reverts directly back into gas and skips the liquid phase (called sublimation in scientific terms). Since there’s no puddles or wet residue, it’s called “dry” ice. Its main use is as a cooling agent for preserving and shipping frozen foods and medicines. Of course, it’s also used in fog machines at theaters (and haunted houses) for dramatic effects.

Dry Ice in Warm Water

Putting dry ice into warm water causes thick, white fog to form and hang on top of the water and then pour over the sides of the container. It also causes the water to carbonate, or bubble, like a mad witches’ brew.

According to Continental Carbonic Products, Inc., a leading dry ice manufacturer and distributer in the US, 1 pound of dry ice will create 2-3 minutes of fog effect. The hotter the water the more fog, but the quicker the dissipation of the ice. 

Obviously, those numbers are for a relatively small container of water and only one pound of dry ice. To turn your swimming pool into a fog machine for any significant length of time, you’re talking hundreds of pounds of dry ice. 

Health Hazards of Dry Ice

According to the New York State Department of Health, dry ice is hazardous for people both externally and internally. Because it’s so cold, it will burn skin similar to frostbite and should always be handled with gloves, and, if chipping to cutting dry ice, goggles or a face shield should be worn as well. Some people put dry ice in Halloween drinks to give that spooky effect — don’t drink it until the ice is gone or else you could get cryogenic burns down your throat!

Also, since dry ice is made from carbon dioxide, which is toxic, breathing in the gas can cause suffocation. Putting dry ice in your pool causes the mist to hang right above the water where a swimmer’s head is, leading to possible unconsciousness and asphyxia. Using dry ice in an indoor pool is especially dangerous because the gas will fill the enclosed space.

Too Much Carbon Dioxide in Pools

Maintaining the right pH level and alkalinity level is essential for a healthy swimming pool. When you fill your pool with dry ice, the added CO2 disrupts the water’s chemical balance. Specifically, it raises the acidity and lowers the pH levels. This has multiple negative effects on your pool and on the people who enjoy it:

  1. Irritated skin. High acidity and low pH dries out your skin and eyes, leading to itchiness and irritation.
  2. Pool surface damage. Increased acid in the water damages pool surfaces and liners, causing wear and tear to occur quicker than if your pH is well-balanced.
  3. System corrosion. Acidic water also corrodes pool filtration systems, whether metal or plastic, your pipes, filters, screws, etc., will corrode and need replacement. Any rust buildup or plastic disintegration will also contaminate and possibly discolor the water.
  4. Higher expense. To return your pool to the proper chemical balance, you will have to add more chemicals to even it out. This, plus any repair or replacements of pool parts due to damage, will give your wallet a hit.


Instead of using dry ice this Halloween, consider renting or buying a fog machine or a mist machine. This will ultimately be safer and cheaper, and the fog output will last much longer — hours before you need to refill the machine versus minutes before you have to add more dry ice to warm water.

If you already bought dry ice and must use it, save your pool and instead use barrels, coolers, or buckets for your dry ice/warm water mixture container.