# NPT safe rocks



## Rusalka (Jun 11, 2008)

Hi there,

I'm just getting started on the planning of a new 10 g setup and I'm wondering if all the knowledgeable people here can give me some types of rock that are NPT safe. I've used Slate in my 20g, but am wondering what else will work? Thanks!


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## bradac56 (May 9, 2007)

Any hard rock will work for an aquarium (not just NPT) as long as you boil it first.
Make sure it's not porous and does not crumble to the touch and you'll be fine.

- Brad


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## dwalstad (Apr 14, 2006)

I believe that almost any natural, surface rock is safe. Your chances of getting a rock that contains something truly harmful (arsenic, mercury, copper, etc) are just about nil. In the rare instance that dangerous rocks are prevalent in an area, they would have leached these metals into the groundwater and poisoned people's well water, so you would be forewarned that rocks in the area might be a problem. I know that my well water is good, so I deduce that the rocks on my property are good, too.

Also, rocks that might increase water hardness shouldn't be a major concern. Neither calcium nor magesium (the components of water hardness) are toxic, and you can always measure water hardness if you suspect the rocks are releasing these chemicals. You'd only find these rocks in desert areas with very little rainfall. I live in the Southeastern US (North Carolina) where almost all calcium and magnesium carbonate rocks were dissolved eons ago.

I've used many different types of rocks (lava, quartz, slate, basalt, phyllite, etc) from my property-- added directly to the tank. No boiling necessary!

I have recently started studying geology and found it fascinating. Rocks are cool!


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## Rusalka (Jun 11, 2008)

Thanks Diana, Rocks ARE cool!! I wish I knew more about geology - very interesting. Glad to know most of them will be just fine in my tank - hunting for cool things to use in your aquarium is half the fun! 

What about using rocks from the ocean? I know that there are alot of different types of rock that you could potentially find in the ocean - but could salt or other minerals leach into a seemingly safe rock and cause trouble in a fresh water tank? What about rocks found in the Great Lakes, which are kind of polluted? 

I read somewhere about a test, where you submerge the rock in vinegar and if it sends up small bubbles then you know not to use it. Has anyone else heard of this, or is this an old wives tale?


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## Sunstar (Sep 17, 2008)

here's a dumb question. what is NPT?


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## mommyeireanne (Oct 24, 2007)

Here in SW Ohio we have _lots_ of limestone. It has a calcium component of fossilized critters. It can affect pH. Likewise, we have very hard, very alkaline water in our underground aquifers.
If you have soft, acidic water, maybe you want some limestone or similar rocks that could help with this. You can find sandstone in many LFSs. It shouldn't affect raise pH.
The vinegar experiment should work because vinegar is low pH. I doubt you'd need to submerge it. I'd use something clear and set it in a bit. Rocks that bubble/react could raise the water pH. 
When I was a kid (at the local museum) we tested rocks with a tiny drop of 
hydrochloric acid/HCl/muratic acid, to see if they were quartz (inert) or calcite (reactive). That stuff could burn skin. The adult teacher had the acid BTW.


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## Rusalka (Jun 11, 2008)

So it's true then! I doubt there is much limestone anywhere in Toronto but it would still probably be interesting to check. Thanks!


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## dwalstad (Apr 14, 2006)

NPT means Natural Planted Tank-- I think. 

I just just "Googled" Toronto/geology/limestone and found several discourses on limestone (see paragraph from one document below), so I would assume Toronto, unlike Southeastern USA, has plenty of limestone. I know parts of Kentuckky, Wisconsin (and now SW Ohio) have hardwater and thus, probably limestone deposits. Something about glacier activity? The Southeast where I live is ancient and well-weathered plus the glaciers didn't get down this far south.

My _Rocks and Minerals_ book says that vinegar works on powdered limestone. Just a few minutes ago I put a piece of coral into pure vinegar and it started to slowly dissolve releasing little crumbs and a tiny bubbles. With a stronger acid, it would surely fizz.

Of course, even in a limestone area you should find plenty of non-limestone rocks-- dark grey basalt, whitish quartz, etc.

Rocks formed millions of years ago, before human pollution. So if you find a rock in a polluted place, it should be perfectly fine. Just give it a quick scrub to get off any outside goo.

PARAGRAPH FROM ARTICLE ON TORONTO AND LIMESTONE:

In southern Douglas County several faults and sharp structures have been observed in the Douglas Group and the Oread Limestone. Rich (1932a) first described these features as follows: South of a curved line marked by sharp flexing and faulting, which for several miles of its course closely follows the northern arc of a circle of about a 4-mile radius, the Toronto Limestone is missing; the Leavenworth Limestone is thicker than average and the Heebner Shale is abnormally thick, 16 feet instead of 6. The Plattsmouth Limestone at several places along the arc was faulted so that south of the fault it lies at the same level as the Toronto Limestone north of the break. These relations indicate (a) uplift of the area south of the curved line so that the Toronto either was not deposited or was eroded after deposition; (b) a renewal of movement, causing a relative sinking of the area south of the fault line while the Leavenworth Limestone and Heebner Shale were deposited; (c) deposition of Plattsmouth Limestone over all the area; and finally, (d) post-Plattsmouth faulting with downthrow to the south.


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## huntersponyfarm (Sep 25, 2008)

Hi, you can just put a few drops of vinegar on a rock and if it fizzes then the rock is probably not safe for the aquarium as it will probably dissolve and/or add minerals to the water. If you get rocks from a fresh or salt water source you run the risk of critters and disease. I soak my rocks in a dilute bleach solution overnight. Then, rinse them completely. I use a dedicated scrub brush to make sure any lichens, dirt or debris is removed. Rinse some more. If you use rock that has lots of holes, pores, or crevases, you should take extra care to clean them. Boiling is an option, 1-2 minutes should kill anything clinging to them. Let them cool before you rinse them off or cold water may break them. Good luck!


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## mommyeireanne (Oct 24, 2007)

A rocks n minerals book is a good idea. And I'm sure your library has one. Remember that Quartz and Calcite can look exactly alike and occur in the same areas. They have the same colors, and the same cleft. Maybe same scratch mark? Can't remember. But it's good to test with an acid. I remembered the HCl because it was dramatic. Sounds like vinegar is a good solution. (har har, -sorry) 
DW: Here in SW Ohio, our main water source (the aquifer) is in the Great Miami River Valley. When the glaciers were melting, they slid down into the valley and left all the rock that they carried, behind. Rainwater on the well-fields goes down through and sits in all the limestone. Maybe it's good for our bones.


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## mommyeireanne (Oct 24, 2007)

And wasn't Rusalka the water nymph character?


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## Rusalka (Jun 11, 2008)

Diana - interesting stuff re: Toronto limestone. I did the same google search and there is indeed lots of limestone in the area! Then I remembered that the Niagara escarpment which runs along the west of Toronto is a great example of a limestone outcropping. Also there is alot of clay and sedimentary rock in the area, which I understand is also a hallmark of a limestone rich area. I'll have to try and ID the rocks I find - luckily the acid/bubble test has now been confirmed by several people on this forum - thanks guys! 

mommyeireanne (did I spell that right?) I found some stone ID charts that will help me figure out what I've found, thanks for the suggestion! Also, here's the wikipedia write up for Rusalka "According to most traditions, the rusalki were fish-women, who lived at the bottom of rivers. In the middle of the night, they would walk out to the bank and dance in meadows. If they saw handsome men, they would fascinate them with songs and dancing, mesmerise them, then lead the person away to the river floor to live with them." Now - I don't know if you'll ever catch me dancing in the dark to capture hot guys, but I do fall under the "fish-woman" description! haha! Also, it is the name of one of my favourite operas, which is actually where I got the idea for my forum name.


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## Rusalka (Jun 11, 2008)

Hopefully I can find some big chunks of whitish or translucent quartz - that would look cool!


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## mommyeireanne (Oct 24, 2007)

I was asking about the Divorak Opera but couldn't remember the name- duh. After goggling it I saw they are the same. I don't know much about opera, but I think of that character every time I see your posts. Its a cool and appropriate moniker.


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