Scuba Diving Gas Mixtures: What You Need to Know

Scuba Diving Gas Mixtures

As a scuba diver, whether professional or recreational, you need to be aware of the different gas mixtures available. You’ll also want to know what each one offers. Each of the scuba diving gas mixtures has its own advantages and disadvantages. Some are more economical, while others are safer.

In this blog post, we’ll discuss the three most common scuba diving gas mixtures: air, nitrox, and trimix. We’ll explain the benefits of each mixture and help you decide which one is right for you.

What is a gas mixture and what are they used for?

Whenever a scuba diver dives underwater, they are breathing gas in one of several forms of gas mixes. While breathing gases sounds like a simple thing, the mixture of gases and their concentrations is critical.

A gas mixture is a combination of gases that have been designed to meet the needs of scuba divers at different depths.

The three primary scuba diving gas mixtures are air, nitrox and trimix. While we’re at it, we’ll discuss pure oxygen as well, although it is not a mix.

Compressed Air.

The most common scuba diving gas mix is compressed air, which is composed of 21% oxygen and 79% nitrogen. There are other trace gases in compressed air, such as Argon. However, they make up less than 1% of the gas blend. This is the same as the atmospheric air we breathe every day, just compressed to fit into a tank.

Compressed air scuba tanks are the most economical option and are widely available in dive shops.

Because nitrogen can cause decompression sickness (DCS) at great depths, air scuba tanks should only be used for dives up to 40 meters or 130 feet in depth. Of course oxygen toxicity can occur in different people at varying depths, this is just a good rule of thumb to reduce the risk of oxygen toxicity.

Nitrox blend.

The next of our scuba diving gases is nitrox, which contains more oxygen and less nitrogen than air. The most common nitrox mix is 32% oxygen and 68% nitrogen, but it can also be blended with other gases that increase the amount of oxygen.

The advantage of using nitrox is that it reduces the risk of DCS by decreasing the amount of nitrogen scuba divers breathe in. Nitrox scuba tanks can be used for dives up to 95 feet. That’s because there is more oxygen in the mix, which helps scuba divers stay underwater for a longer period of time but becomes toxic at shallower depths.

One thing to remember, however, is that nitrox scuba tanks must be carefully monitored and have regular maintenance to ensure the gas is pure.


The last scuba diving gas mixture is trimix, a blend of helium, an inert gas, oxygen, and nitrogen. Trimix scuba tanks are most commonly used for deeper dives because there is less oxygen. Of course, more technical divers use this scuba diving gas mixture because the helium helps to reduce nitrogen narcosis and stay safe during deep dives.

Pure oxygen.

Last on our list is pure oxygen. Sure, all gas mixes have varying levels of oxygen content. However, pure oxygen scuba tanks are the real deal with only oxygen. This scuba diving gas must only be used for decompression purposes or at very shallow dives. Breathing only oxygen at deep diving depths can cause oxygen toxicity.

What is the suitable gas mix for you?

That depends on what type of scuba diving you do. If you’re doing some recreational diving, air scuba tanks are the most economical and widely available option. They’re easy to use, easy to obtain, and usually much cheaper.

As for technical and commercial diving, nitrox scuba tanks are the preferred scuba diving gas mixture. This is because they reduce nitrogen narcosis and DCS risks. While trimix scuba tanks can be used for deeper dives, they require more training and maintenance than nitrox scuba tanks.

The dangers of oxygen toxicity.

As a diver, it’s important to know about the dangers of oxygen toxicity. While scuba diving gas mixes such as nitrox and trimix can reduce the risk of DCS, they also increase the risk of oxygen toxicity. Therefore, it is important to be aware of your scuba diving gas mixes and how much oxygen you are breathing in at any given time.

One way you can know exactly how much oxygen is in your scuba tank is to use a dive computer. Dive computers measure the gas mixture and depth of your dive so you can be sure you are staying within safe levels of oxygen for scuba diving.

The importance of gas analysis.

One of the most important things scuba divers should remember is gas analysis. Whenever scuba divers fill their scuba tanks with a scuba diving gas mixture, they should always have it tested with a gas analyzer for purity to ensure that the right blend of gases is present and that there are no contaminants.

Once scuba divers have verified that their scuba tanks are filled with a scuba diving gas mixture that is suitable for their dive, they can go ahead and enjoy the underwater experience.

Ultimately, scuba diving gas mixes offer both technical and commercial diving as well as recreational diving scuba divers a variety of options when it comes to exploring the depths of our oceans. With the correct information and careful consideration, scuba divers can find the scuba diving gas mixture that best suits their needs.

Always dive safely.

One thing scuba divers should always keep in mind is dive safety. Before you scuba dive, ensure that all your scuba diving gear has been properly checked and maintained. This includes your scuba tanks filled with the right scuba diving gas mixture for the job. When breathing gas mixtures scuba diving, always pay attention to your dive computer. You’ll want to ensure you stay within safe oxygen limits.

Remember to employ dive safety protocols like buddy checks and safe ascent rates. That way, scuba divers can enjoy a fun and safe scuba diving experience.