how can you tell if it is black iron?

I hear bad things about tanks made of black iron. I would guess that a magnet will tell you whether or not a tank is aluminum, but if the magnet sticks, is there a way to figure out if it is steel or black iron?

same material...just a different coating....google it

STEEL, BLACK IRON , doesnt matter , whay counts is how well the tank was built , mounted ,coated and how well it is protected from water leaks.

Good inspection ports , proper baffels and a water sump are part of how well the tank is built.

Dont bother to look on an entry level boat .

The term is "black iron" very loosely used, so I wouldn't read a lot into it. It is still just carbon steel.

But to answer the OP's question: If you have a metal tank with a black outer surface that is attracted to a magnet, then you have a black iron tank.

seattleboatguy said:

I hear bad things about tanks made of black iron. I would guess that a magnet will tell you whether or not a tank is aluminum, but if the magnet sticks, is there a way to figure out if it is steel or black iron?

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They do not make true black iron any more and they have not since the 30's. Your tank is made out of hot roll low carbon steel. The trem "BLACK IRON" is just slang like in black iron pipe.

That slang trem comes from the layer of high temperature paint they place on the steel. The black piant is just a protective oxide layer that helps block any progessive corrosion.

A magnet will stick to your tank. The bad things you heard about black iron tanks is more based in the fact of BLACK RUST! Black rust is ferrous oxide unlike RED RUST ferric oxide which is seen in galvanized pipes.

In time the black piant will break down, which mean you will have to replace the tanks at some point. Until that time filters will clean up the water for you so you can drink it.

If you are seeing RED RUST now. I would replace the tank becuase that mean the Black piant is gone and your tank is rusting out.

F.F. nailed it when he said look at the way it is built.

All the best to you

happy cruising to all

H. Foster

FF said:

Good inspection ports , proper baffels and a water sump are part of how well the tank is built.

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What would you consider to be a good sump design? Would it be simply a matter of a tilted lower tank surface so any debris collects at that low point, or would it be something more exotic?