# Rocks containing iron



## Magdelaine (Apr 9, 2005)

I have two nice rocks that I would like to place in my tank (and attach plants to), but I'm afraid they will rust. Is this a problem in an aquarium?

They are a very porous volcanic rock, like pumice, but I think they very high in iron content because they are dark, heavy, and seem to have rust stains on them. They also smell like rust.


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## Hamm3592 (Apr 24, 2005)

personally i wouldnt risk putting them in your tank. But if you really want to i would wash them (without soap) and put them in a separate tank for a while with a fish in there and see how he does. if he's still fine after a while then you can probably put it in ypur main tank.


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## Fishfirst (Jan 24, 2005)

don't put it in your tank. I would first do a test with some vinigar and see if it bubbles/leaches anything into the vinigar mixture.


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## Magdelaine (Apr 9, 2005)

I put them in a vinegar bath and they seemed to be totally non-reactive. I think the only issue is rust... They are probably mostly silica anyway, being volcanic. They have these really cool holes, like a sponge, all through them that would probably be great for growing bacteria...


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## Lexus (Jan 19, 2005)

hmm is it like the red volcanic rock you can get at a pet store?


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## Magdelaine (Apr 9, 2005)

Yikes, I have no idea what those are. These are black, not red (except for the parts that sat in the dirt), and they were gathered from an actual volcanic dome.


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## TheOldSalt (Jan 28, 2005)

The iron isn't really the main problem. Your plants will gobble it up anyway. The big problems with iron are iron toxicity if you don't have enough plants or make enough water changes, and of course algae just love the yummy nutrients in lava. ( if it doesn't kill them first. ) Ferrous bacteria might even turn your tank into a pool of rusty slime. 
( You've possibly seen creeks with rust colored globs/strings in them? )

The iron can be dealt with by using a lot of plants and/or making a lot of water changes.

There are other things in lava, though, which are a lot more noxious, but since volcanoes aren't all alike, it's hard to say just what properties you lava will have. Zinc, sulful, nickel, molybdenum, silicate... the list is very long. Not many of these things are especially troublesome in trace amounts, and are indeed essential, but it's hard to predict just what any given piece of lava will dump into the water and in what concentration.

I have seen tanks full of lava rock which looked just fine, and I've seen some which were a complete disaster. As such, I can only advise caution and careful observation along with lots of regular water changes. Use a lot of plants to try to prevent an algae epidemic.

Be ready for anything.


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## Magdelaine (Apr 9, 2005)

Oh good, I'll just see what happens, then. A pool of rusty brown slime is definitely NOT what I have in mind! Although I'm going to use low light/easy plants I do plan on it being fairly heavily planted, so hopefully it will be a good balance. Thanks!


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## fishbone (Jan 15, 2007)

I'm reviving this old thread because I don't want to start another one on a very similar topic.
Has anyone used volcanic rock from places like Menard's or Home Depot? My father bought a bunch for landscaping purposes and I was pondering stealind maybe 3 at most for my 10g planted aquarium.
They're red, light and very porous. When I saw those pores I immediately thought great for beneficial bacteria growth. They're not the strongest rocks, I rubbed two of them hard together and got them to start breaking down.


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## Betta1 (Jan 5, 2007)

I have a bunch of lava rock in my 55g, never thought twice about it as being a problem cause I just guess my concept of these rocks doesn't lend it's self to that. I got a touch worried reading this thread but it's been about 2 months since I added it and absolutley nothing has changed in the tank. Like TOS said it can vary greatly from rock to rock, so far as appearance it's exactly as you've described but it sounds like that doesn't matter so much.


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