The Second Stage Regulators That Serve as a Backup Breathing Device for Scuba

The Verdict, and the Basis for It

A reliable backup breathing device ensures you have a redundant air source that remains easy to operate even when your primary gear fails. Having a dedicated octopus means you do not have to worry about complex mechanics during a high-stress situation.

The Sea Elite Scout Compact Octopus provides a dedicated safety solution with a 40-inch yellow braided flexible hose for easy reach. If you require a different brand’s ecosystem, the SEAC X100 Octopus is a strong mid-range alternative, while the Brownie’s Third Lung Second Stage Regulator serves a specific niche for third-lung users.

We selected these three models after screening 16 Second Stage Regulators and comparing 10 models here at Scuba Forge. The shortlist covers a price range from $102.49 to $129.95, while the median price of the 10 products in our comparison is $151.85.

See the essential minimum requirements to ensure the device meets your safety standards.

Find answers to common inquiries in the FAQ section.

Use the comparison table to see the technical specifications side by side.

Second Stage Regulators for Scuba Diving Emergencies Compared Side by Side

Prices are approximate and move frequently – check the current price before deciding.

The Sea Elite Scout Compact Octopus fits this topic best because it provides a 40-inch hose and a 5.2 oz weight for pony bottle mounting.

Each Pick for Scuba Diving Emergencies, Reviewed

The 3 picks below are reviewed in the same order as the cards above.

Sea Elite Scout Compact Octopus

The Sea Elite Scout Compact Octopus is a dedicated backup breathing device designed for portability and simplicity. It was selected for this list because it prioritizes a small footprint and ease of use for emergency situations over the high-flow performance of a primary regulator.

What we like: This model weighs only 5.2 oz, which is light enough for a pony bottle setup where buoyancy and weight distribution are priorities. The 40-inch yellow braided flexible hose provides a clear visual reference and sufficient reach for an emergency air source. It also features a soft push silicone purge cover, which helps clear water from the mouthpiece during a purge.

Keep in mind: The construction is primarily ABS and polycarbonate, which is standard for backup units but lacks the high-end materials of primary gear. This model is best suited for divers who need a lightweight, dedicated safety source rather than a high-performance primary.

Brownie’s Third Lung Second Stage Regulator

Brownie’s Third Lung Second Stage Regulator is a specialized backup unit that functions as a redundant air source. We included it here because it is specifically engineered as a “Third Lung” to provide a reliable emergency breathing option in compact configurations.

What we like: This unit offers a 40-inch hose length, matching the reach of the Sea Elite model. It carries a 5.0 rating from buyers, indicating high satisfaction with its performance as a backup device. The design allows it to serve as a reliable secondary source when a primary regulator fails.

Keep in mind: Specific compatibility details are not listed in the provided data, so you should confirm your specific model’s requirements before purchasing. It is intended for those seeking a dedicated safety device rather than a primary breathing regulator.

SEAC X100 Octopus Second Stage Regulator

The SEAC X100 Octopus Second Stage Regulator is a high-visibility backup breathing device. It is included for its low-friction mechanics and lightweight construction, making it a reliable choice for emergency scuba gear.

What we like: This model features a 2nd stage Venturi control, a mechanism that helps regulate air flow to the user. Its high visibility color makes it easy to locate in a high-stress situation. The use of techno polymers and ultralight alloys helps keep the weight down for easier integration into a backup setup.

Keep in mind: The specific weight and hose length are not provided in the data, so you must verify these dimensions against your specific pony bottle configuration. This model is ideal for divers who prioritize visibility and smooth mechanics in their emergency gear.

Backup vs. Standard Second Stage

A standard second stage is designed for primary breathing with high flow and durability, while a dedicated backup regulator like these “Octopus” units focuses on compact size and ease of use. You should choose a dedicated backup if you need a small, easy-to-access air source for a pony bottle or redundant setup. If you require a device to be your primary source for the duration of a dive, a standard regulator is the appropriate choice.

How the Sea Elite Scout Compact Octopus weight-to-performance ratio benefits pony bottles

The Sea Elite Scout Compact Octopus has the best weight-to-performance ratio for a pony bottle because it weighs only 5.2 oz. Lower weight reduces the buoyancy and weight distribution issues that can occur when mounting a backup source on a harness. If your pony bottle setup is weight-sensitive, prioritize a model with a lower weight value like this one.

How the 40-inch hose length affects your backup regulator setup

Measure the distance from your primary tank to your intended backup mounting point and compare it against the 40-inch hose length of these models. If your distance is less than 40 inches, these hoses will provide sufficient reach; if it is greater, you may need a longer extension.

Before making a final purchase, be sure to review second stage regulator warranty terms for long-term peace of mind.

What Matters Most in a Second Stage Regulator for Scuba Diving Emergencies

Compactness for Pony Bottle Mounting

Prioritize a compact design with a weight under 8 oz to ensure the backup breathing device does not hinder your mobility when mounted on a pony bottle. The Sea Elite Scout Compact Octopus weighs 5.2 oz, providing a low-profile profile for an alternate air source. While high-end engineering benchmarks like the Apeks XTX offer superior flow, they often exceed the portability requirements of a dedicated backup unit. If you are mounting this on a small cylinder, the 3.25 by 2.5 inch dimensions of the Sea Elite model provide a smaller footprint than many standard second stage regulators.

Ease of Breathing During High-Stress

Evaluate the mechanism for low-friction movement to ensure consistent gas delivery when you are under stress. The SEAC X100 Octopus utilizes low-friction mechanics and a Venturi control—a system that uses the flow of air to help regulate delivery—to maintain steady breathing. While the Brownie’s Third Lung Second Stage Regulator does not state its internal mechanics, its role as a dedicated backup focuses on reliability in emergency scenarios. High-end models like the Scubapro S620 Ti are known for smooth, consistent flow, and these picks aim to provide similar reliability in a simplified, redundant configuration.

Purge Efficiency for Clearing Water

Check for a dedicated purge cover or high-visibility housing to quickly clear water from the mouthpiece during an emergency. The Sea Elite Scout Compact Octopus includes a soft push silicone purge cover to facilitate clearing the airway. For those requiring a more visual interface, the SEAC X100 Octopus features a high visibility color to help you locate the device quickly in low-visibility water. These features allow you to clear the second stage quickly, which is a primary requirement for any backup breathing device.

How ABS and polycarbonate materials provide durability against salt corrosion

Select materials like ABS, polycarbonate, or specialized elastomers to ensure corrosion resistance for saltwater durability. The Sea Elite Scout Compact Octopus uses a construction of ABS and polycarbonate to resist environmental wear. The SEAC X100 Octopus utilizes techno polymers and elastomers to maintain structural integrity in marine environments. Because these materials are chosen for their ability to withstand salt, they provide a reliable way to ensure your backup gear remains functional over time. Unlike technical or sidemount configurations that may require specialized maintenance, these units are designed for straightforward, durable use in recreational saltwater diving.

Why backup regulators have limited air consumption at depth

A backup regulator consumes air based on your breathing rate and the depth at which you are using it, but because these devices are for emergency use only, you should plan for a very limited reserve life. Since the data does not state specific flow rates for these models, you should rely on your primary air source for the majority of your dive and treat these as a secondary safety measure. In a real-world scenario, a diver would first realize they need to switch to their alternate air source, reach for the octopus, and begin breathing from the pony bottle. They would then monitor their remaining pressure and signal their buddy to begin an immediate ascent.

Explore the detailed reviews for a deeper look at each individual product.

Review the article scope to see what products are included in this list.

Identify the perfect match for your needs using the audience checklist.

Divers seeking a reliable backup can see how the Rego LV4403B46R Regulator performs in various conditions.

What Each Job Calls For vs What These Picks State

Match the job you actually need done to the figure it calls for, then check which picks state that figure or more. Where none do, the row says so.

These figures are the levels this category is generally held to, not manufacturer claims. A pick at or above a figure states that number; how it reaches it and the rest of your setup still decide the job, so check them against your own workload before buying.

Who Buys Second Stage Regulators, and What It Really Costs

View our curated selection of the best models in our top picks.

Check the setup and warranty notes for technical requirements and support details.

Consult the buying guide to understand the key factors for making a choice.

Understanding the different designs is easier if you study the types of second stage regulators available today.

Before the First Use, and After Delivery

Required first stage and high-pressure hose components for regulator operation

You must have a functional first stage and a compatible high-pressure hose to connect the backup breathing device to your air source. The hose provides the high-pressure air path from the cylinder to the second stage.

• The Sea Elite Scout Compact Octopus requires a connection to an air or Nitrox (up to 40) compatible system.
• The SEAC X100 Octopus uses a Venturi control system, which regulates gas flow based on the pressure differential between the intake and exhaust.
• The Brownie’s Third Lung Second Stage Regulator is designed to fit specific models; you should check your specific model number to ensure it is the correct fit.

What to Check on Arrival

Warranty and return policies differ by seller and country. Verify these details before the return window closes to ensure you are covered for any defects.

• Check the hose length of the Sea Elite Scout Compact Octopus to confirm it is the 40-inch braided flexible hose, as this determines your reach.
• Verify the mouthpiece and purge cover on the Sea Elite Scout Compact Octopus are intact, as these are the primary points of contact for breathing.
• Confirm the high-visibility color and material of the SEAC X100 Octopus to ensure the unit is not showing signs of surface damage.
• Ensure the Brownie’s Third Lung Second Stage Regulator matches your specific hardware requirements, as compatibility is the primary factor for this model.

Perform a dry purge and check for any leaks at the connection point before your first dive.

You can also examine the Rego LV4403B4 Regulator spec breakdown to see how it compares to other models.

Questions Buyers Ask Before Choosing Second Stage Regulators for Scuba Diving Emergencies

Which backup breathing device is the most compact for travel?

The most compact size for a travel-friendly backup is the Sea Elite Scout Compact Octopus, which measures 3.25 by 2.5 inches. This small footprint allows the device to be easily stowed in a gear bag without taking up significant space. Will it fit in your smallest equipment kit? The Sea Elite Scout Compact Octopus weighs only 5.2 oz, making it a lightweight option for mobile divers.

Can a standard regulator be used as a backup?

A standard regulator can be used as a backup, but it is not a dedicated octopus designed for redundant breathing. While the primary regulator provides the main air source, a dedicated backup like the Brownie’s Third Lung Second Stage Regulator is specifically engineered for emergency use. These specialized units prioritize ease of use and high visibility over the performance specs of a primary breathing apparatus.

Which scuba octopus is best for a backup air source?

The best scuba octopus for a backup air source depends on your specific weight requirements for the pony bottle setup. The Sea Elite Scout Compact Octopus provides a 40-inch yellow braided flexible hose for easy routing. If you prefer a specialized design, the Brownie’s Third Lung Second Stage Regulator also provides a 40-inch hose length for redundant breathing.

Which emergency breathing device is most affordable?

The most affordable emergency breathing device is the SEAC X100 Octopus Second Stage Regulator, priced around $102.49. It utilizes techno polymers and high visibility colors to ensure it is easy to locate in a low-visibility situation. This model offers a balance of low-friction mechanics and a 4.7 rating from 4 buyers.

Who Should Skip These Second Stage Regulators

If you are looking for a high-performance primary regulator, these backup units may not provide the flow rates required for continuous primary use. These models are specifically designed as “Octopus” or “Third Lung” units, meaning they are engineered for redundancy rather than as your main breathing source.

You should choose a different class of equipment if you require high-end engineering benchmarks for reliability and flow, such as the Apeks XTX or Scubapro S620 Ti. For those seeking specialized configurations, see our guide on best second stage regulator for extreme environments.