Aluminium vs steel tanks

[Tigerman]

I don't know about California, but around here, you can easily pick up an Al80 for $75 from somebody who's decided to upgrade to a steel tank.

Having read this in another thread I started to think a little and the question that popped into my mind was as follows;
What makes steel tanks an upgrade vs an aluminium tank?
Im not very "technical" as far as tanks go, I just bought what I was recommended, which was a Scandinavian Model 232 bar tank. "If its steel, its Faber"..
So, why would a steel tank be an upgrade vs an aluminium tank and whats the differences?

 

[mike_s]

Steel is denser and its bouyancy characteristics are different in the water. The tank will be less bouyant or "weigh more" in the water. The advantage of this is that you don't require as much weight on your waist for the dive.

Using a stell 80 or 100 for example you might be able to reduce your weight off your waist by maybe 6 pounds (+/-) on average.

They also can be a higher PSI rating, or hold more air in a more compact size compared to aluminum. (meaning you get more cubic feet of air in a slightly smaller tank). The tank walls are thinner which helps this. They can be thinner because steel is stronger than aluminum.

The reason you see people "upgrading" is that the Aluminum 80 is the most common tank found out there and is most widely used for instruction and rentals. This is the most typical tank bought. Some divers make the change to steel later and decide they like those much better and sell the Aluminum tanks.

 

[redacted]

If the "upgrade" is designed to get more gas, that will also tend to move you from aluminum to steel. As a WWW (warm water wimp), I'm looking to upgrade but will probably seek an Al100 as even the LP steels will leave me negatively bouyant for much of my diving.