Aluminum tanks are available for a cheap price. They are very resistant to corrosion and normally use standard valves. They are a bit longer than comparable steel. However, they do not require a boot to stand upright; although some divers add a special boot which contains a lead weight in order to counter positive buoyancy. Most types are rated 3000 psi.
Steel tanks are more diverse in their buoyancy and corrosion characteristics. They do not all use standard valves. Some HP versions use a "DIN" valve. The PST HP tank holds 3500 psi, uses a DIN valve, and is fairly compact. These tanks are also relatively light with only slight negative buoyancy. They are very corrosion resistant with hot dip galvo exterior coating. The Faber HP tank is fairly rare but they are seen among dry suit divers. For this reason, they seem to be popular in England and some other lands. They are extremely heavy and negatively buoyant. Either DIN or standard valves can be fitted to these 3490 psi tanks. The Faber tanks are fairly resistant to corrosion with paint over metallized galvo. Most steel tanks are fitted with boots which increase drag to a minor degree and trap moisture which, over a period of time, can produce a whitish corrosion on galvo and blisters on painted tanks.
Several companies sell LP tanks under various brands. Most are manufactured by PST or Faber. They have varying degrees of buoyancy and are of the same general characteristics as above. Of the two major steel lines, some LP Fabers are nearly as buoyant as aluminum tanks while PST are all slightly negative. Either standard or DIN valves can be fitted. Their pressure ratings run to 2640 psi.
