What tank is best like deco for SM configuration

[viders]

Hello,
I'm using SM with dry suit and two 12l (200bar) steel bottles. Bottles are pretty slight and easy (12,9kg). I would to buy third bottle for deco gas (usually EAN50). What will be the best in my configuration to hold best trim?
I have to buy same size of steel bottle or smaller steel or al80? Thanks for any advice.

 

[DevonDiver]

Capacity is really gonna be dictated by the diving you will be doing. That's basic gas consumption maths.

Most people I know opt for aluminum deco cylinders. Steel (primary) cylinders are used to form part of your overall weighting strategy for cold water; where thick wetsuits or drysuits require significant ballast carries. Deco cylinders may be staged or removed during the dive, so they shouldn't form part of that strategy.