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Author Topic: Are any rocks bad for a fish tank?  (Read 3971 times)

Offline aaronjunited

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Are any rocks bad for a fish tank?
« on: 13/02/2011 17:50:03 »
Hi everyone, i'm not a student or someone who is very much interested in rocks. Im lookin help indentifying rocks and help with wether they will be safe to put in a fish tank.

I know some rocks may contain harmfull things that can kill fish, so im lookin advice really.
Hopefully you can all help me.

I'l put some pictures up of rocks i seen at the garden centre.
Thanks in advance. Some of these pictures arent great, but hopefully they are enough for a guess.


I thought this was a limestone rock, as it was really yellowish.


Was told this one was quartz, it was very smooth to touch.


No idea what this was, but it was really dark red/brown colour.
« Last Edit: 09/04/2011 14:44:36 by chris »


 

Offline aaronjunited

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Re: Are any rocks bad for a fish tank?
« Reply #1 on: 13/02/2011 18:12:13 »
I have some more pictures, i collected this lot from the beach. No idea wat so ever what any of them are, hopefully someone can help.

rock 1


rock 2


rock 3


rock 4


rock 5


rock 6


rock 7


rock 8


different view of rock 8


rock 9 - looks like slate??


rock 10



Please can someone identify if these may be safe in an aquarium, and what they are.
Thanks.
 

Offline Mazurka

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Re: Are any rocks bad for a fish tank?
« Reply #2 on: 14/02/2011 11:42:00 »
The received wisdom I rely on is to generally avoid any rocks with a high calcium or magnesium carbonate content, such as limestone, dolomite, coral etc. as they will disolve over time and increase the pH of the tank and the hardness of the water (especially in tropical tanks). 

The best way to test this is either with strong vinegar or diluted acid (such as hydrochloric) which is probably avaliable from a chemist if you ask.  If it fizzes or bubbles when the acid is applied it is too calcic for the aquarium.

With respect to ID -ing the rocks pictured, always tricky from photos but rock 10 is undoubtedly brick.

For rocks gathered on the beach, I wash them a couple of times by leaving in a bucket overnight and then drying in the sun, to try and avoid introducing an unknown quantity of salt or other contaminants into the tank (although I do add a little salt deliberately for Goldfish)  I would not recomend baking them as some people suggest. 
 

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Re: Are any rocks bad for a fish tank?
« Reply #2 on: 14/02/2011 11:42:00 »

 

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