How to Choose Your Cylinder

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 woolly information and advice about diving cylinders.

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

Aluminium or Steel?

Steel advantages

  • Lighter than an Ali
  • Slightly smaller than an Ali

They are negatively buoyant so you need less weight on our weight belt.

Steel disadvantages

  • Negativity buoyant so they tend to roll you over all the time
  • 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

Aluminium Advantages

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

Aluminium disadvantages

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


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 you buy a biggy.