Is this rock safe for my tank ?

Discussion in 'Beginner Discussions' started by Zippy320, Feb 13, 2018.

  1. Zippy320

    Zippy320

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    Hi guys
    Its been a long time , anyway a lot has happened and I have decided to restart my tank , Although this time I will be taking a different approach and need to incorporate Rocks and plants into my Discus tank .

    Problem is the LFS are terrible in their prices for good sized rocks and most sell terrible pieces .

    I was wondering if this rock will be safe for my tank?
    Im in Durban so its not to far from me .

    http://www.ballitocrushers.co.za

    They say that its Dolerite , I think its the same type or rock thats used for building , driveways etc .

    Is this safe for aquarium use? Im sure if I go to the quarry , I could find a few good pieces to use .

    Thanks guys for all the responses .

    Zippy320
     
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  3. OP
    Zippy320

    Zippy320

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    Not sure how to edit my previous post but this is what they say about their rock, Taken from the site.

    The quarry is situated in the cane fields of northern KZN. We are fortunate that the farm on which we are situated and its surrounds has a good supply of dolerite. Dolerite is a volcanic rock. A fine-textured, dark-gray to black igneous rock composed mostly of plagioclase feldspar (labradorite) and pyroxene and exhibiting ophitic texture. It is commonly used for crushed stone. Dolerite is an intrusive igneous rock; that is, one which has "invaded older rock and may displace or dilate the pre-existing rock".

    Dolerite is formed below the Earth's surface, a form of basalt, containing relatively little silica (mafic in composition). Dolerite is a medium-grained (hypabyssal) basalt and forms in shallow intrusions, such as dykes, which cut across the rock strata, and sills, which push between beds of sedimentary rock. When exposed at the surface, dolerite weathers into spherical lumps.

    Dolerite is a coarse black or dark greenish crystalline rock. Crystals in dolerite can be up to 5mm in length. The minerals in dolerite are rich in iron so it weathers a dark rusty brown. Dolerite is a very hard, heavy rock that makes an excellent road stone. Dolerite is an intrusive igneous rock, cooled slowly beneath the ground. It can also be injected violently into the crust in sheet-like structures called dykes. These are associated with pulling apart of the crust, creating gaps which are filled in by molten rock which then cools to form dolerite. It is an Igneous rock, with a grain size < 1 mm (extrusive). It is a basic rock, with a total silica content of 45-55%.

    Is this safe?
     
  4. f-fish

    f-fish #unspecified

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  5. BBFish

    BBFish Born to Fish Keeping ..... Forced to work

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    I do not know the chemical composition of Dolerite, but a simple vinegar acid test can be a used to test if it will "leak" harmful chemicals:

    Get some clear table vinegar and drip some into a small pool on the surface of the stone, leave for five minutes and see if the area has fizzed as the vinegar dissolves the stone. If it does, do not use this stone.
     
  6. Reedfish

    Reedfish Moderator

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    Most rocks are safe for tanks.
    The big exception being rocks that contain metals should not be used.

    Rocks composed of or containing limestone will react to a drop of vinegar, as mentioned above.
    But this isn't 100% conclusive. If the rock has small/trace amounts it may not react strongly to the vinegar, but may still slowly leach into the water.
    Not ideal for soft water fish such as Discus, SA Cichlids, Rays etc. But for hard water fish such as Rift Cichlids, livebearers etc, this is advantageous.
     
  7. OP
    Zippy320

    Zippy320

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    Thank you soo much! When I have time , I will be going over to the quarry , worst comes to worst , if the are not suitable , I guess my mum could use them somewhere in the garden haha .

    Thanks so much for the tip on protecting the glass bottom , I will look into that. Im going to set this up in my Jewel Vision 450 tank . The bottom glass does look thick but , I would rather not take any chances. Its going to be a long process . I honestly dont plan on keeping fish in the tank untill after a few months . my first step would be to remove whatever fish are still living in the tank over to my Jewel rio 300 , strip this tank down compleatly and start it from scratch .

    Will be posting a lot more here in the future . Thanks so much!
     
  8. JvH

    JvH aka FishBait

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    Hey @Zippy320 . I'm a bit late to the party here, but I'll chime in anyway. I'm an engineering geologist and do quite a bit of work with dolerite (both in hard rock form sourced from quarries where they blast the rock for road aggregate, and in borrow pits where the dolerite has broken down to form soil which is used in the lower layers of the road. The guys in construction often call this doleritic soil "sabunga"). As you will be getting your rocks from a quarry, you will be sourcing fresh, unweathered rock which won't break down in your tank. In terms of it's chemistry, see the table below which shows average chemical compositions of the Drakensberg Group dolerites (which occur in the Durban area). Hopefully this helps in making your decision.


    Drakensberg dolerite chemistry.JPG
     
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  9. OP
    Zippy320

    Zippy320

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    Hi JvH

    Thank you so much for your post and help! Thats very interesting ! I really appreciate your help. Im still not sure if its safe for the tank . Will go over and collect a few pieces , test them and see how they behave .
    Based on the above info , I hope someone could chime in and tell me if its safe or should I keep away . It all looks very confusing to me :)
     
  10. Double-D

    Double-D David

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    I am not a rock engineer but do have a chemical background. If I am correct in my assumption I would say that the oxide combinations as shown in the table destabilize in water thus leeching minerals that could be harmful in high enough concentrations. That being said... I could be wrong.
     
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  11. OP
    Zippy320

    Zippy320

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    Thanks so much for your insight into that rock Double - D , Truly appreciate it , I read your post this afternoon while on my phone and this swayed me into buying two bags of large size ( not to large though ) Tigers eye rock for my tank :) I do have this in the tank , a few pieces and it had no adverse effect on my previous fish . All I need now is a nice large piece .

    I feel a little more at ease with the tigers eye though .
     

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