Steel V.S. Aluminum Tanks

One of the questions I often get asked is why I dive with steel tanks and what are the benefits. So why would you buy steel?

The pro’s for steel tanks

Steel tanks have a couple of benefits. Their buoyancy characteristics are one of the greatest benefits. Some of you might not know why they tell you to do a buoyancy check with an empty tank. The reason is that an empty tank is more buoyant then a full tank. This means you need to add extra lead to you to stay under while diving. A steal tank often stays negatively buoyant when empty whereas an empty aluminum tank can be 5lbs more buoyant. This means if you are diving with a steel tank you don’t need to add the extra weight to your BCD which give you better buoyancy control.

Another benefit is higher volume steel tanks that are almost the same size or smaller than an aluminum tank. Steel is a lot stronger than aluminum. Because of this the walls of a steel tank can be a lot thinner, giving you more space for air.  A 120cft steel tank is about the same size than an 80cft aluminum tank, but gives you 40cft more air and a longer dive time. For shorter individuals a regular 80cft tank can be too tall, whereas an 80cft steel tank is shorter making it a better fit.

The con’s for steel tanks

The price is the biggest con. Steel tanks can be twice as expensive as aluminum ones. Even second-hand steels keep their value. The other issue is rust on the inside. Aluminum tanks seldom corrode on the inside, but if you drain a steel tank and let moisture get in the tank they will rust. In practice this isn’t a big issue as you should never drain a tank completely. You should minimally leave 500psi in your tanks to keep moisture out.