Metal tongs in reef. Problem?

[acabgd]

After a few years of reefing I have noticed I am using metal tongs to move things around the tank. I've never really thought about it, but although they're supposed to be stainless, lately I've noticed some rust on edges.

That scared me a bit - is it safe to use at all in the tank? I know about copper and other metals in general, but what about these? Does anyone else use metal tongs in their tank?

[bob1968]

I been using them for 8 years
They have some rust
Never had a problem

[thegrun]

+1, use steel wool and then wipe them down with alcohol if it gets bad.

[acabgd]

Phew... ok, thanks a lot guys!

[Boston21]

Just wipe them down really well when you are done with them, might limit the amount of corrosion that will happen.

[acabgd]

Originally Posted by Boston21

Just wipe them down really well when you are done with them, might limit the amount of corrosion that will happen.

Yeah, I've noticed if I wash them in freshwater and wipe them down thorougly the surface rust patches come off and don't come back until I get lazy again

[disc1]

As long as you're not leaving them in the tank when you're done...

[Reefer54]

you can always buy new ones for 3 bux from China on ebay.

[acabgd]

Originally Posted by disc1

As long as you're not leaving them in the tank when you're done...

Of course not. I might not be very smart, but I'm not that stupid

[dkeller_nc]

Perhaps more info than you want to know, but...

All "stainless steel" isn't created equal. There are at least 10 different alloys in common use, and perhaps a 50 or more that have been created and given SAE grades. All of these alloys have different chromium content - it's the chromium that gives SS most of its "stainless" properties.

Depending on this chromium content, the steel may or may not be marine-grade. For example, 316 SS will not corrode in continuous seawater immersion, while 304 SS will.

So perhaps this may help if someone is reading this and considering which SS tool to buy to use in their tanks.

There is one other aspect of SS use in corrosive environments that is applicable to us: passivation. Many SSs will corrode if used in their fresh-from-the-manufacturer state. Without getting too involved in corrosion engineering, the basics are that the chloride ion attacks the iron in the SS surface and starts to form pits. These pits expand into full-bore rust.

But if the alloy has sufficient chromium content, the surface can be depleted in iron content, which has the effect of enriching the chromium content. This process is called passivation.

There are several ways to accomplish passivation for your reef tools and/or stainless fittings and screws. The fastest way to do it is to coat/soak the tools and parts in phosphoric acid (10% is concentrated enough to do it). Naval jelly, commonly available in auto parts stores, contains phosphoric in sufficient concentration to passivate SS. Another way is to make a solution of approximately 5% citric acid, soak the parts in it for 20 minutes, remove them from the solution, and allow the remaining citric acid to air-dry on the parts. They can then be rinsed with water to remove any remaining citric acid.

The passivation layer will remain intact through use and washing with detergents. However, if the surface is abraded through, for example, scrubbing with a scouring pad, the surface must be re-passivated.

[sh0ck]

or u can use pure iron ones and help with PO4 removal

[Boston21]

Originally Posted by dkeller_nc

Perhaps more info than you want to know, but...

All "stainless steel" isn't created equal. There are at least 10 different alloys in common use, and perhaps a 50 or more that have been created and given SAE grades. All of these alloys have different chromium content - it's the chromium that gives SS most of its "stainless" properties.

Depending on this chromium content, the steel may or may not be marine-grade. For example, 316 SS will not corrode in continuous seawater immersion, while 304 SS will.

So perhaps this may help if someone is reading this and considering which SS tool to buy to use in their tanks.

There is one other aspect of SS use in corrosive environments that is applicable to us: passivation. Many SSs will corrode if used in their fresh-from-the-manufacturer state. Without getting too involved in corrosion engineering, the basics are that the chloride ion attacks the iron in the SS surface and starts to form pits. These pits expand into full-bore rust.

But if the alloy has sufficient chromium content, the surface can be depleted in iron content, which has the effect of enriching the chromium content. This process is called passivation.

There are several ways to accomplish passivation for your reef tools and/or stainless fittings and screws. The fastest way to do it is to coat/soak the tools and parts in phosphoric acid (10% is concentrated enough to do it). Naval jelly, commonly available in auto parts stores, contains phosphoric in sufficient concentration to passivate SS. Another way is to make a solution of approximately 5% citric acid, soak the parts in it for 20 minutes, remove them from the solution, and allow the remaining citric acid to air-dry on the parts. They can then be rinsed with water to remove any remaining citric acid.

The passivation layer will remain intact through use and washing with detergents. However, if the surface is abraded through, for example, scrubbing with a scouring pad, the surface must be re-passivated.

Wow Might have to try that out sometime

[wolfblue]

Originally Posted by dkeller_nc

This process is called passivation.

Not TMI for me Thanks

--John

[Paul B]

Metal tongs in a reef? OMG!

[disc1]

In defense Paul that's aluminum. And I know I heard you say that it had been in saltwater for a while before it went into your tank, which effectively does the same sort of passivation that dkeller was talking about.

[Paul B]

Dam

[Boston21]

Originally Posted by Paul B

Dam

Haha

[dkeller_nc]

Originally Posted by disc1

In defense Paul that's aluminum. And I know I heard you say that it had been in saltwater for a while before it went into your tank, which effectively does the same sort of passivation that dkeller was talking about.

Yep - metals like aluminum, copper, zinc, etc... form oxide layers that are highly resistant to corrosion. These form naturally in air, though there are many types of industrial processes used to speed this oxide formation up.