# Sandstone in a planted aquarium



## WildKat (Sep 26, 2014)

I found some of these rocks and I know they are sandstone, but I am wondering if they would be okay in my planted tank. I posted them in a Facebook page about planted tanks and have gotten very mixed answers, so I was hoping that by posting it on here, I would get some better answers. 

I also was wondering if they would affect the balance in my tank, what if I sprayed them with clear pond sealant? Would this work for them or no?

Thanks in advance.


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## lilnaugrim (Mar 27, 2013)

Most of them are inert but unless you know the exact make-up of the sandstone (what kind of sand and other minerals are in the rock) then I wouldn't use it. Some sandstone will just disintegrate in water while others are fine. Test them first in buckets of water, one per each. Check the rock for any signs of crystal forms or anything metallic--those would be toxic. Check the pH 24 hours after soaking and check the rock for any sort of disintegration, also if you can check calcium levels, iron, and--well basically just check everything you can, Hardness and Alkalinity too to see if it changes the water.


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## Aqua Aurora (Oct 4, 2013)

Don't use sandstone, it won't stay in a 'stone' state too long, just make a mess in your tank.


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## lilnaugrim (Mar 27, 2013)

Not all sandstone will erode or breakdown. You just want to make sure there is no calcium in the rock, you can test it with Vinegar to see if it fizzes, that's the vinegar reacting with the calcium carbonate.

But if you don't know exactly where it came from, don't use it, not worth it. If you do want to try, just do the bucket method where you soak it for two weeks or more and check all the parameters.

Here's a quote about sandstone:

"Sandstones can vary greatly in their chemical composition.

This is due to the fact that the sand is cemented together by various minerals which have been formed in the pore spaces in the rock. The most common “cements” are calcite, iron or quartz. Sandstones, on the whole, are inert in water, although the cement type will dictate their strength and mineral composition.

The most important factor to consider when utilising these rocks is their porosity and often fragile nature. Sandstones bonded with iron will remain stronger over time than those containing calcite: the latter tending to crumble after a period of submersion.

The high porosity of sandstones leads to the containment and release of toxins/chemicals acquired from an aquatic environment. You need to be sure of their source."

http://www.sydneycichlid.com/aquarium-rocks.htm


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## BettaMummy87 (Jul 26, 2014)

Those look pretty iron-rich too (quite a lot of red in some of them). Whilst they will crumble much slower than the more dangerous calciferous varieties, those high iron levels will still (almost certainly) leach into the water, which will cause problems. It may not be now, but down the line it could well become a real issue. More disolved anythings, including iron, will raise Hardness, which can, in turn affect your PH. Thing is, if this only starts to be an issue later on, is the first thing you are going to take out to correct it going to be the rocks? Most people, probably myself included, will look at something much newer rather than something that has been there the whole time. 

Its worth knowing the risks. I know the vast majority of aquarists avoid the risk completely by not using sandstone. Its unlikely anyone ever really knows what is in the sandstone. 

No joke, licking it could clue you in to whether there are unwanted metals in it. if it tastes at all metallic, then its a definite no. It is a quick test used by geologists, but just because it doesn't will not guarantee it is free from harmful metals.

Personally unles it was a quartz-based one, I would be tempted to leave it.


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## WildKat (Sep 26, 2014)

What is your guys's opinion on using a clear pond sealant over the tops of the rocks?


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## BettaMummy87 (Jul 26, 2014)

Its an interesting idea. In theory, yes it should work. I have been thinking about it whilst I went fry-stuff shopping (for the mollies that have invaded my tank). So long as it is decently covered, I would expect it to stop or at least significantly hinder any release of anything. If you coat it well, havent missed anything and remove it if they do show any signs of errosion or cracking, it _should_ be worth a shot.


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