Scuba tanks are highly versatile pieces of equipment with numerous applications: in the military, ship and aquarium maintenance, marine biology, underwater photography, airsoft, underwater archaeology, and much more. Of course, it is also crucial for recreational and technical scuba diving. With so many practical uses, one must find a reliable fill station so that they can fill their tanks affordably.
There are a lot of initial costs involved when one is first starting out with scuba diving. Divers must first get certified, then purchase all of the necessary scuba gear, and even after that, there are still some recurring costs. For instance, divers must continue to pay to enter the dive locations, pay for travel expenses, and of course, pay to refill their scuba tank. If they want to use enriched air nitrox or trimix, then they must be certified in the requisite courses or else the dive shop won’t let them fill the tank. So how much does it cost to refill a scuba tank?
The cost of refilling your scuba tank depends on the size of the tank and the type of air you want to fill the tank with. Also, different dive shops charge different prices, sometimes as part of their promotional and marketing strategies. As such, prices can vary widely depending on where you are in the world and the gas mix used. In this article we will discuss the various factors that can change the cost to fill a tank as well as provide estimates for how much it might cost you to fill your scuba tank.
Size of Scuba Tank
It should be obvious that a larger tank can hold more air and therefore costs more to fill up than a smaller tank. Also consider the type of tank it is: steel or aluminum. Steel is a stronger material than aluminum, and at the high end, steel tanks can hold more air than aluminum tanks. You have to know what the maximum fill pressure of your tank is regardless of what material it is made from.
Which scuba cylinder you should own depends on what kind of diving you intend on doing as well as personal preference. Larger cylinders are heavier, are difficult to carry out of the water, and affect your buoyancy underwater.
Below are the three most commonly used sizes and tank types. These sizes are standardized throughout the world, so there should not be any unusual variations. Typically the “size” of a tank is not measuring its literal size, but rather the maximum air capacity it can hold in units of cubic feet (abbreviated as cf or cu ft).
100 cu ft (232 bar) Steel Tank
100 cu ft steel cylinders are the standard tank type and size used by a majority of divers. They are available in two sizes (physical dimensions), however they should still hold the same amount of air and thus cost the same to fill.
80 cu ft (207 bar) Aluminum Tank
Recreational divers tend to gravitate towards the 80 cu ft aluminum tank. The reason for this is that aluminum tanks are much more affordable, and this one in particular is a smaller size. Furthermore, aluminum tanks become positively buoyant as the air is consumed, so it is easier and safer to reach neutral buoyancy.
25 cu ft (232 bar) Emergency Tank
Reserve tanks are optional, but it’s always nice to have a redundant air source in case of an emergency. These mini scuba tanks, also known as pony bottles or emergency tanks, are compact and smaller versions of regular tanks. They are typically mounted to the side of the main tank. You can get them in 300 bar versions for even more air capacity.
Other sizes
Not all tanks have the same maximum fill pressure. Ninety percent of aluminum 80 tanks are 3,000 psi (207 bar), but not all. Most steel tanks are 3,442 psi (232 bar), but some are 3,500 psi. Hopefully the dive shop staff are checking to verify, but not all aluminum 80 tanks are 3,000 psi. If you know what yours is, let the staff know just in case.
Scuba Cylinder Air Pressure
Typically the cost of filling a tank is calculated per cubic foot.
There are two common types of scuba tanks: ones that can withstand 300 bar of air pressure (DIN tanks) and ones that can only withstand 232 bar of air pressure (Yoke). DIN is more frequently used in European destinations whereas yoke is typically used in North America. Lower pressure 207 bar tanks are available as well.
The major difference between these tanks is that tanks with higher maximum fill pressures can carry more air, therefore cost more to fill, and weigh more when full. Keep in mind that not all dive shops are able to fill a 300 bar tank because it requires highly specialized equipment.
Types of Gas Mixes
Another factor that affects how much filling a tank costs is the type of breathing gas you plan on using. Scuba tanks can be filled with:
Compressed Air: This is simply filtered, clean air that has been highly compressed to fill a tank.
Nitrox: A combination of oxygen and nitrogen, which can help decrease the chance of experiencing decompression sickness on a prolonged dive.
Trimix: A combination of helium, nitrogen, and oxygen typically used by deep or technical divers. With helium in the mix, the chance of experiencing nitrogen narcosis is reduced. Helium is significantly more expensive than nitrogen and oxygen. Trimix is used for deep diving because it does not cause narcosis.
Filling compressed air is extremely straightforward and thus very affordable. Filling nitrogen is a more arduous process that requires the cylinder to be cleaned first, so dive shops typically charge more (and have a minimum charge) for filling both nitrox and trimix.
Dive shops strive to provide clean breathing gas for their customers because even a tiny amount of contaminants can reach toxic levels when compressed. This is the reason why you should fill your tank up at a reputable business, and not one operated out of someone’s garage. The filters used by the compressors must be able to catch all of the contaminants or else you might be in trouble.
Some common contaminants are carbon dioxide, carbon monoxide, and trace amounts of any lubricants used to maintain the compressor.
No matter what gas mix you use, even standard air, you should check your scuba cylinder using a nitrox analyzer before you dive. Oxygen analyzers will display the O2 content of your gas mix, and the readings should be what you expect (e.g. 21% for standard air, 32% for EAN32, 36% for EAN36, etc).
Estimated Cost to Fill a Scuba Cylinder
Now that you know all of the factors that can change how much it costs to fill a scuba tank, let’s talk about prices. Again, the price will vary from location to location, and the numbers provided below are just estimates.
| Gas Type | Capacity | Price |
| Compressed Air | Any Capacity Up to 207 bar | $5 |
| O2 Clean Air* | For cleaning, any capacity | $10 |
| Nitrox | 0-40 cu ft | $3 to $9 |
| Nitrox | Up to 80 cu ft | $5 to $20 |
| Nitrox | Up to 100 cu ft | $7 to $27 |
| Nitrox | Up to 120 cu ft | $10 to $32 |
| Helium | 1 cu ft | $3 |
| Oxygen | 1 cu ft | $0.40 |
* We mentioned that prior to filling a tank with Nitrox or Trimix, the tank had to be cleaned. Dive shops perform a specific cleaning process using special solutions to clear any flammable substances for the cylinder and valve before filling the tank with O2 clean air. This process is crucial because pure oxygen can become flammable if it comes into contact with certain substances in our daily life. Dive shops charge for this cleaning service on top of the cost of adding in the nitrox and trimix.
To sum everything up, dive shops charge you based on the type of gas (or gas mix) you want to fill the tank with as well as the capacity of your tank. An extra charge will be added if they need to perform a cleaning service.
Furthermore, filling a half-full tank is different from filling an empty one. That’s why the table above varies depending on how much air is present at the start. There isn’t a distinction for compressed air since it is cheap enough to fill nearly any capacity no matter how full or empty it is.
As we mentioned, helium is much more expensive than nitrogen and oxygen. Thus, dive shops sell helium by cubic foot. The total cost will depend on the blend chosen for the depth you will be diving at, and the cost will be calculated accordingly. For instance, some trimix blends require 35% helium which will be comparatively cheaper than a blend that consists of 50% helium.
Closing Remarks
Based on the factors above, the cost of filling a scuba tank can be as low as $5 or it can be nearly $200 if you are doing a trimix blend with a large percentage of helium. For the vast majority of divers, you can expect filling a tank to cost around $10 to $20. If you are willing to shop around, you may be able to get prices even lower than that. If you dive frequently, this seemingly small savings can add up over time. Recreational divers can just pay the higher price or rent a tank.
If you are interested in finding the best scuba tank in each size range, then read this review for more information.