Pony Bottles & Backup Scuba Systems: The Ultimate Guide

The Ultimate Safety Net: Everything You Need to Know About Pony Bottles & Backup Systems

Scuba diving is built on the foundation of the buddy system. If you run out of air, or experience a catastrophic gear failure, your buddy is your backup life-support system.

But what happens if your buddy is distracted taking a photo? What if the visibility drops and you get separated? Or what if, in a panic, your buddy's air supply is also running dangerously low?

Relying entirely on another human being for your primary emergency backup is a calculated risk. For divers who want to remove that risk and take absolute control of their own survival, there is only one answer: a redundant air supply.

At Paragon Dive Store, we outfit a lot of divers with backup systems. Whether you are an aspiring solo diver, an underwater photographer who tends to wander, or just someone who wants ultimate peace of mind, here is everything you need to know about pony bottles and backup breathing systems.

1. What is a Pony Bottle? (And What It Isn't)

A pony bottle is a small, independent scuba cylinder that you carry alongside your main tank. Crucially, it has its own dedicated first stage and second stage regulator, and its own submersible pressure gauge (SPG).

If your primary regulator free-flows, your tank O-ring blows, or you simply mismanage your gas, you do not need to swim to a buddy. You simply reach down, put your pony regulator in your mouth, and make a safe, controlled ascent to the surface, complete with a safety stop.

Pony Bottle vs. "Spare Air"
It is vital to distinguish a true pony bottle from micro-bailout devices (often sold under the brand name "Spare Air"). Those micro devices typically hold 1.7 to 3.0 cubic feet of air. While excellent for escaping a crashed helicopter in 15 feet of water or to make an emergency ascent, they generally do not hold enough volume for a recreational diver to make a slow, safe ascent—including a 3-minute safety stop—from 100 feet deep.

A pony bottle is a true redundant system designed for standard recreational diving depths.

2. Sizing Your Backup: How Much Air Do You Need?

Pony bottles are usually aluminum cylinders and come in a few standard sizes. The right size depends on your maximum diving depth and your breathing rate.

• 13 Cubic Feet: The absolute minimum we recommend for shallow recreational diving. It is very compact, but only provides enough gas for a direct, controlled ascent from about 60 feet.
• 19 Cubic Feet: The "Goldilocks" size for most recreational divers. It is relatively lightweight, easy to travel with, and provides plenty of gas to safely ascend from 100 feet, including a safety stop, even at a slightly elevated breathing rate.
• 30 & 40 Cubic Feet: These are larger, heavier cylinders (a 40 cu ft is essentially a standard decompression bottle). These are necessary for deep recreational dives (130 feet) or light technical diving where you need significant volume to get home.

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3. How to Mount It: Tank-Mount vs. Slung

Once you have your cylinder, you have to decide how to carry it. There are two primary schools of thought:

The Tank Mount (Back-Mounted)

Using heavy-duty metal brackets or cam bands, the pony bottle is clamped directly to your primary scuba cylinder.

• Pros: It keeps your chest area completely clear. You don't feel it dangling.
• Cons: You cannot easily see the pressure gauge or reach the tank valve if it needs to be turned on or off. It also adds a lot of asymmetrical weight to your back, which can throw off your trim. It is also difficult to manage on small dive boats.

The Slung Mount (Side-Mounted)

This is the method overwhelmingly preferred by technical divers and the staff at Paragon. The pony bottle is rigged with bolt snaps and clipped to the D-rings on the chest and waist of your BCD.

• Pros: Complete control. You can see the SPG at all times. You can easily turn the valve on or off. You can unclip it and hand it to a panicked diver. It is highly aerodynamic and doesn't roll you onto your side.
• Cons: It adds a piece of gear to your front, which takes a dive or two to get used to.

4. Rigging the Regulator: Keeping it Clean

You don't want a massive web of hoses tangling you up. A pony bottle regulator setup should be minimalist.

• The First Stage: Choose a compact, unsealed first stage to save weight and space.
• The Second Stage: Use a standard second stage. It should be secured to the pony bottle using a bungee necklace or a breakaway clip so it doesn't drag in the sand.
• The Gauge: Ditch the long high-pressure hose. Use a "Button Gauge" (a tiny SPG that screws directly into the first stage) or a gauge on a very short (6-inch) high-pressure hose. You only need to check this gauge before the dive and during an emergency.

5. Who Should Carry a Pony Bottle?

While any diver can benefit from the peace of mind, pony bottles are highly recommended for:

• Underwater Photographers: Photographers are notorious for getting "tunnel vision" while framing a shot, sometimes losing track of their buddy or their air supply.
• Solo Divers: If you hold a Self-Reliant Diver or Solo Diver certification, a redundant air source is a mandatory piece of life-support equipment.
• Deep Wreck/Cave Divers: If you frequently dive in the 90-130 foot range, the surface is a long way away. A pony bottle helps ensure you can make it back safely.
• Anxious Divers: If you have anxiety about the "what ifs" of equipment failure, carrying your own backup supply is the fastest way to relax and enjoy the dive.

The Final Step: Practice

Buying a pony bottle doesn't make you safer—knowing how to use it does. Once you have your system rigged, take it to a pool or a shallow shore dive. Practice deploying the regulator, turning the valve on, and breathing from it while hovering.

Ready to build your ultimate safety net? Visit us at Paragon Dive Store. We can help you choose the right cylinder size, rig the slinging hardware perfectly for your BCD, and build a streamlined regulator package that you’ll barely notice you are carrying—until the moment you need it most.