Seconde Stage

Scuba Regulator Second Stages

The scuba regulator second stage is the component divers breathe directly from during a dive. It reduces the intermediate pressure coming from the first stage to ambient pressure, ensuring smooth, natural and reliable underwater breathing.

At MOMODIVE you can find a selection of second stages for scuba regulators dedicated to recreational diving, technical diving, sidemount and DIR configurations.

Our catalog includes balanced second stages, adjustable models, Venturi systems and configurations compatible with cold water and Nitrox diving.

What Does the Second Stage Do?

The second stage works as a demand valve, delivering air only during inhalation while maintaining natural breathing performance at any depth.

This system allows divers to:

• ensure smooth and natural breathing
• reduce breathing effort underwater
• optimize comfort and performance
• manage recreational and technical diving configurations
• maintain stable air delivery even at depth

The quality of the second stage directly affects breathing comfort, safety and overall diving performance.

Balanced and Adjustable Second Stages

Our catalog includes different configurations dedicated to specific operational needs and diving environments.

Venturi System and Breathing Adjustment

Many second stages include Venturi systems and breathing adjustment controls.

These systems allow divers to:

• improve airflow performance
• reduce inhalation effort
• optimize breathing at depth
• reduce the risk of freeflow at the surface
• customize breathing comfort

Adjustable configurations are often preferred for technical and advanced diving.

Second Stages for Technical Diving and Sidemount

Technical diving and sidemount configurations require reliable and compact second stages designed to provide high breathing performance.

Our catalog includes dedicated configurations for:

• sidemount diving
• DIR diving
• stage and decompression cylinders
• twinset manifold systems
• rebreather bailout systems
• deep diving

Technical second stages are designed to ensure stable breathing performance even in demanding underwater environments.

Second Stages for Cold Water Diving

Some models are specifically designed for cold water diving thanks to anti-freeze systems and dedicated configurations.

These systems allow divers to:

• reduce freezing risk
• maintain high performance in cold water
• improve underwater reliability
• manage technical and deep diving conditions

Cold water second stages are especially appreciated in technical and winter diving environments.

Available Brands

At MOMODIVE you can find second stages selected from some of the most appreciated brands in recreational and technical diving.

• Scubatec – reliable and easy-to-service second stages designed for recreational and technical diving
• Halcyon – second stages dedicated to DIR configurations and advanced technical diving
• Apeks – among the most popular regulators for cold water, sidemount and technical diving
• Atomic Aquatics – high-performance second stages designed for exceptional breathing comfort and premium build quality

Compatibility and Diving Configurations

Second stages are compatible with the main scuba regulator first stages and can be used in different diving configurations.

• recreational diving
• technical diving
• DIR diving
• sidemount setups
• stage and decompression systems
• Nitrox configurations

Regulator Accessories and Components

Complete your setup with accessories and components dedicated to scuba regulators.

• Complete regulator sets
• Regulator accessories
• LP regulator hoses
• Regulator spare parts and service kits

Second Stage Servicing and Maintenance

Regular servicing of the second stage is essential to ensure safety, reliability and correct underwater performance.

Periodic maintenance helps maintain high breathing performance and reduces the risk of malfunctions during dives.

Learn More About Scuba Regulators and Diving Configurations

• Scuba Regulators: Complete Guide to Selection, Maintenance and Servicing
• Scuba Regulator Servicing: When to Do It and Why It Matters
• Piston or Diaphragm? Guide to Choosing the Right Scuba Regulator
• Cold Water Regulators: Complete Guide for Safe Diving
• Best Scuba Regulators: How to Choose the Right Model

Frequently Asked Questions About Second Stages

What is the difference between a balanced and unbalanced second stage?

Balanced second stages maintain more consistent breathing performance regardless of the remaining tank pressure.

What is the purpose of the Venturi system?

The Venturi system improves airflow performance and reduces breathing effort during inhalation.

Are second stages compatible with Nitrox?

Yes. Many models are Nitrox compatible and also available in O2 clean configurations.

How often should a second stage be serviced?

Service intervals depend on manufacturer recommendations and usage, but servicing is generally recommended every 12 months or after a specified number of dives.

Second Stages for Recreational and Technical Diving

From recreational diving to advanced technical diving setups, choosing the correct second stage directly affects breathing comfort, safety and underwater equipment management.

Explore the available configurations and choose the second stage best suited to your diving needs.