# Aquarium safe metals?



## Danno79 (Mar 14, 2011)

I attached some of my java ferns and annubias to some pieces of drift wood (didn't soak them first). I was wondering what type of metal is safe to put in aquariums so that I can either put a screw in each piece or I was thinking maybe fishing weights. Any input?? Thanks

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## koebwil (Jul 6, 2011)

Titanium or platinum are the only truly inert metals, though I have heard stainless steel works. Just keep in mind water is the universal solvent, and stainless means it will stain less, not that it is magically corrosion proof. any solution involving plastic will be better, but again it depends on the type of plastic.


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## wkndracer (Mar 14, 2009)

316L will last longer than any of us will live


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## Danno79 (Mar 14, 2011)

Thanks. This will only be temporary, I just want to weigh them down long enough to become water logged. 

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## willknowitall (Oct 3, 2010)

i think gold and silver pretty safe too :hihi:


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## firefiend (Sep 3, 2009)

galvanized will work great... I usually use some lag bolt on pesky driftwood... or silicone it to some slate rock on the bottom.


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## willknowitall (Oct 3, 2010)

galvanised hmmm zinc who knows what else, bad idea


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## firefiend (Sep 3, 2009)

willknowitall said:


> galvanised hmmm zinc who knows what else, bad idea


There is practically no leaching of zinc from the galvinization process. Even if left in the tank for years the zinc wouldn't accumulate to anything near detrimental... then if your doing water changes there's even less to worry about.

I've never experienced a problem with it, though I've just started keep plants. At any rate I can safely say from experience that fish aren't sensitive to it (at least the species I've kept.)


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## willknowitall (Oct 3, 2010)

they put zinc metal strips on roof tops , the water leaches zinc to kill mosses
also what other metals are mixed in to there galvanized concoctions


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## firefiend (Sep 3, 2009)

Free zinc ions are definitely toxic, as is Zinc Oxide, one of the stages of galvinization. The finished product is zinc carbonate.

I have enough experience to safely say it will not negatively affect your fish if you do a monthly 10% water change. I'm also confident that it will not harm your fish with fewer water changes.

They're shouldn't be any other metals mixed in because the zinc carbonate finish is what you're actually after... it's what makes the bolts and nails look dull grey. Other metals would generate a different compound and negate the purpose of galvinization.

No worries either way... there are other methods to accomplish the same goal.


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## willknowitall (Oct 3, 2010)

hmmmmm sound like you know more then me 
do you have any idea what the effect of carbonic acid is on zinc carbonate
lime calcium , phosphates nitrates etc
what is the purity of this zinc carbonate compound when applied steel


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## Ben. (Mar 29, 2011)

I used stainless steel, just use something that people have had experience with.


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## firefiend (Sep 3, 2009)

willknowitall said:


> hmmmmm sound like you know more then me
> do you have any idea what the effect of carbonic acid is on zinc carbonate
> lime calcium , phosphates nitrates etc
> what is the purity of this zinc carbonate compound when applied steel


As far as I know it is pure molten zinc with some lead mixed in to promote the fluidity in coating. I'm not sure of the exact % but in my experience it seems no different than the lead weights used to keep plants down.

this lead, since its mixed with the zinc leaches very little. 

I'm not sure about carbonic acid, to be honest. Lime Calcium would generally have no effect in aquarium use and I wouldn't expect any difference with phosphates, nitrates, etc. Galvanization is meant to me highly non-corrosive so in terms of general aquarium use I wouldn't expect any problems.


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## willknowitall (Oct 3, 2010)

well to keep this going hahaha , carbonic acid is a major ingredient in planted tanks
lead that doesn't sound good ether
certain shrimp and mosses are highly sensitive to heavy medals
lead weights for plants are almost pure lead. not generally ruled safe


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## firefiend (Sep 3, 2009)

Well, keeping in mind that galvanization's purpose is to prevent corrosion in a great many situations. With this is mind if the lead leeches that means the galvanization is pointless.
But still I can understand being weary if your dealing with shrimp and moss.

Carbonic acid is common enough that I highly doubt it will affect it. I mean we're just talking about CO2, yes I know it's technically H2CO3 but once infused into the water it's just regular old CO2. And while I don't have any practical experience I would be amazingly surprised if the CO2 levels used in plant growth broke down the zinc.


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## HD Blazingwolf (May 12, 2011)

chrome.. same principal as stainless steel. stainless means it has 4 % or more of magnesium bonded to the surface which is corrosion resistant. the higher the level the more "stainless it is" this is how we get different grades of stainless steel.

chrome IS HIGHLY corrosion resistant. i doubt however you want to load up ur fish tank with chrome as its ery expensive


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## nameless? (May 28, 2011)

If you're just using the metal to weigh down some wood for a few weeks/months till it sinks im sure stainless is fine.


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## Danno79 (Mar 14, 2011)

Thanks for all of your replies. Also sweet metallurgy lesson. 

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## 150EH (Dec 6, 2004)

Good stainless steel screws will work and will not rust or corrode, I wouldn't use galvinized metals, these will even kill small birds and chickens and must be wiped with vinegar first to be neutral.


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## wkndracer (Mar 14, 2009)

HD Blazingwolf said:


> chrome.. same principal as stainless steel. *stainless means it has 4 % or more of magnesium bonded to the surface which is corrosion resistant.* the higher the level the more "stainless it is" this is how we get different grades of stainless steel.
> 
> chrome IS HIGHLY corrosion resistant. i doubt however you want to load up ur fish tank with chrome as its ery expensive


Not getting this one? Other than complete error or lack of knowledge. I've made my living welding, nothing is bonded to the surface of the metal. Chrome and nickle content throughout the material is how stainless is graded. I'll post it again, anything 316L will be here long after you're gone. 

Chroming used to be a high dollar, durable finish. When it was a copper, nickle, then chrome used in the process you had something. Now it's 3-5yrs max life. Chrome is a barrier finish that only lasts as long as the finish is not breached. Once breached the base metal (aluminum, carbon steel etc.) oxidizes, rusts or corrodes (pick your term).

Not really understanding the debate on the topic that's developed here as this is not that complicated. Use grade #316 stainless and forget about ever second guessing the choice.


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## koebwil (Jul 6, 2011)

wkndracer said:


> Not getting this one? Other than complete error or lack of knowledge. I've made my living welding, nothing is bonded to the surface of the metal. Chrome and nickle content throughout the material is how stainless is graded. I'll post it again, anything 316L will be here long after you're gone.
> 
> Chroming used to be a high dollar, durable finish. When it was a copper, nickle, then chrome used in the process you had something. Now it's 3-5yrs max life. Chrome is a barrier finish that only lasts as long as the finish is not breached. Once breached the base metal (aluminum, carbon steel etc.) oxidizes, rusts or corrodes (pick your term).
> 
> Not really understanding the debate on the topic that's developed here as this is not that complicated. Use grade #316 stainless and forget about ever second guessing the choice.


I definitely agree that 316L would be the best economic choice here, I was just trying to say that nothing is perfect. I think the confusion with the coating on stainless steel may be coming from the fact that stainless steels create a layer of chromium oxide on their surface. they are usually defined as a steel having at least 12% chromium (except for 409, cause that stuff sucks). As far as galvanized I would be concerned about the thin layer of zinc oxide on the outside of it due to contact with oxygen.


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## firefiend (Sep 3, 2009)

koebwil said:


> As far as galvanized I would be concerned about the thin layer of zinc oxide on the outside of it due to contact with oxygen.



I have no problem with stainless, used it myself. I just don't want galvanized hardware to get a bad rap.

zinc oxide is not present on galvanized hardware. When molten zinc is first applied to the metal it is meant to protect the zinc reacts to atmospheric oxygen and produces zinc oxide, which is toxic. The zinc oxide then reacts to atmospheric hydrogen and the coating now becomes zinc hydroxide, this then reacts with atmospheric CO2 and becomes the dull grey looking item you see in the store, zinc carbonate. From this state it will not revert back to zinc oxide.

So, galvanized screws and lag bolts are perfectly fine for aquarium use.


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## Danno79 (Mar 14, 2011)

I won't even have to buy screws. I have tons of stainless steel jewellery. I'll just use those for weights. 

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