The cylinder has a huge impact on your diving and is a major influence on how much air you use.
There is a lot of misleading information and advice regarding diving cylinders.

In SA we are encouraged to use and buy the biggest cylinders available. This is wrong!

Steel Cylinders

Aluminium Cylinders


  • Lighter than an Ali Cylinder out of the water
  • Slightly smaller than an Ali Cylinder
  • They are negatively buoyant so you need less weight on our weight belt.


  • Negatively buoyant so they tend to roll you over all the time on a dive
  • Prone to rusting especially as in SA we have to stamp the visual inspection every year.
  • Prone to internal flash powdery rust that can damage your regulator


  • Neutrally buoyant so great to dive with…. No roll over
  • No rust or corrosion
  • Does not need a bootie


  • Heavier out of the water
  • Slightly bigger
  • Need more weights on the old weight belt

The Verdict…

We highly recommend Aluminium cylinders over the Steel Cylinders.

The Old Aluminium cylinders are incredibly buoyant and so they gave aluminium cylinders a very bad reputation about how they make a diver float.

Divetek is a proud importer of the Luxfer aluminium diving cylinders. These cylinders are slightly negative at the start of the dive. During the dive they are neutrally buoyant and towards the end of the dive they are slightly positive. See “Our Brands” page for more info on Luxfer Cylinders.

In a nutshell, we would rather have a cylinder that is neutrally buoyant for most of the dive so that you can fly without being rolled over. Towards the end of the dive and the safety stop, you watch your buoyancy very carefully and then ascend slowly. It takes some practice but once you’ve got it right – you will never dive with steel cylinders again!

The smaller the size the less energy you need to move the cylinder through the water and the less air you will use.

Always try and dive with a smaller cylinder!

Women, youngsters and divers who don’t suck air can use a 7ltr for all but deep dives. The best all rounder will be 10ltr.

The 12 ltrs are really in the large and heavy category and 15s are in the tek diving arena.

Adjust your weighting and try an Ali 7l or 10l and you will have a really great dive. Do this BEFORE buying a larger cylinder.

Also attend one of our Advanced Buoyancy Courses where we can teach you some tricks and techniques to improve your air consumption so you don’t have to increase your cylinder size.

Diving cylinders we keep in stock