Dolomite

Discussion in 'Water Parameters and Additives' started by Gustav, 10 Sep 2010.

  1. Gustav

    Gustav

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    Has anyone ever tried using this as a calcium amd magnesium additive? As I understand its a carbonate wich would help buffer the ph aswell. Might be wrong. Also it occurs naturally so can it be that bad? Would there be a build up of some sort after a while of use?
     
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  3. Perky Pets

    Perky Pets Sponsor

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    Aparently the p.h around the dolimite has to be to low for the fish and corals to surive before it desolves the calcium ect out of it .
     
    Last edited: 10 Sep 2010
  4. dallasg

    dallasg Moderator MASA Contributor

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    Will see what neil h has to say our resident geologist.
    The ph won't be An issue as most reactors use low ph to disolve the media
    Posted via Mobile Device
     
  5. Perky Pets

    Perky Pets Sponsor

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    Does he have a reactor ?
     
  6. dallasg

    dallasg Moderator MASA Contributor

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    Yip, but that's how all calcium reactors work
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  7. Neil H

    Neil H Moderator MASA Contributor

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    there is a distinct difference in the crystaline structure between carbonates such as Aragonite (what we typically use) and dolomites, it was a while ago that i last read anything about them, but if i remember correctly dolomite is more stable and thus breaks down slower than carbonates such as aragonite. so while it can be used in a reactor is is not the optimum thing to use .... I have a sneaking suspicion that dolomites typically have more impurities but dont quote me on that one !
     
  8. Neil H

    Neil H Moderator MASA Contributor

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    Also ....

    dolomite is a carbonate
    aragonite is a carbonate

    both are calcium rich they crystal structure is different (in the same way graphite and diamonds are both carbon with different crystal structures)
     
  9. Nemos Janitor

    Nemos Janitor

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    Dolomite is used in carax to add mg. However the problem with most grades of dolomite is that it contains a lot of PO4. This is why it is used with caution. If i am not mistaken the grey media that Deltec add to their reactors contain a very pure PO4 free grade of dolomite.
     
    Last edited: 10 Sep 2010
  10. Perky Pets

    Perky Pets Sponsor

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    I think youve missed the question.
    He doesnt have a calcium reactor on his 60 liter tank ( according to the tank specs )

    I think his wanting to either use dolamite as a substrate in place of aragonite or add it a a powdered additive, which will be p.h sensitive.

    I think calcite is the closest thing to Aragonite.

    Calcite

    [​IMG] )




    Formula:CaCO 3System:TrigonalColour:White, Yellow, Red, ...Lustre:Vitreous, PearlyHardness:3Name: From Calx, the Latin for Lime.Polymorph of:Aragonite, VateriteIsostructural with:Nitratine, Otavite





    <IMG style="BORDER-TOP-WIDTH: 0px; PADDING-RIGHT: 0px; PADDING-LEFT: 0px; BORDER-LEFT-WIDTH: 0px; BORDER-BOTTOM-WIDTH: 0px; PADDING-BOTTOM: 0px; MARGIN: 0px; PADDING-TOP: 0px; POSITION: absolute; BORDER-RIGHT-WIDTH: 0px" jstcache="3" jsvalues=".style.left:$this.imgLeft;.style.top:$this.imgTop;.style.width:$this.imgWidth;.style.height:$this.imgHeight;.src:$this.imgSrc;">
     
  11. deadmeat2016

    deadmeat2016 Wouter

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    Agreeing with neil here as a fellow geologist, aragonite = CaCO3 dolomite = CaMgCO3, being more stable than aragonite means that it will not dissolve unless in a reactor and aragonite doesnt dissolve in the tank, its a common misconception. if u wanna get picky, it does dissolve at a rate of 1g/m3 per million years! dunno if magnesium will leach or whatever.
     
  12. Gustav

    Gustav Thread Starter

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    Thanks P.E. Yes I want to know if dolomite can be used as either a substrate or a additive? And on the subject of impurities what if you used Dischem dolomite tablets? It is hopefully more refined. Just wondering about the PO4?
     
  13. Nemos Janitor

    Nemos Janitor

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    Not sure on the dolomite tablets.

    Just a few words of warning. Be very careful when dosing to lift Mg. If done to quickly you will get a heavy ammonia spike.
     
  14. Perky Pets

    Perky Pets Sponsor

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    Thanks G.

    Try google these minerals, very interesting stuff.:thumbup:


    The carbon dioxide gas (CO2) is given off as bubbles and the calcium dissolves in the residual water. Any acid, just about, can produce these results, but dilute hydrochloric acid or vinegar are the two recommended acids for this test. Other carbonates such as dolomite or siderite do not react as easily with these acids as does calcite and this leads to differentiating these somewhat similar minerals more readily.

    Calcite is intricately tied to carbon dioxide in another way. Since many sea organisms such as corals, algae and diatoms make their shells out of calcite, they pull carbon dioxide from the sea water to accomplish this in a near reverse of the reaction above. This is fortuitous for us, as carbon dioxide has been found to be a green house gas and contributes to the so called "green house gas effect". Environmentally then, calcite is very important and may have been quite important to the successful development of our planet in the past. By pulling carbon dioxide out of the sea water, this biological activity allows more of the carbon dioxide in the air to dissolve in the sea water and thus acts as a carbon dioxide filter for he planet. Environmentalists are now actively engaged in determining if this activity can be increase by human intervention to the point of warding off the "green house gas effect". A significant amount of calcite precipitation in sea water is undoubtedly inorganic, but the exact amount that this contributes is not well known. Calcite and other carbonate minerals are very important minerals in the ocean ecosystems of the world.
    Calcite is not the only calcium carbonate mineral. There are no less than three minerals or phases of CaCO[SIZE=-1]3[/SIZE]. Aragonite and vaterite are polymorphs (latin for "many shapes") with calcite, meaning they all have the same chemistry, but different crystal structures and symmetries. Aragonite is orthorhombic, vaterite is hexagonal and calcite is trigonal. Aragonite is a common mineral, but is vastly out distanced by calcite which is the more stable mineral at most temperatures and pressures and in most environments. Vaterite on the other hand is extremely scarce and rarely seen. Aragonite will over time convert to calcite and calcite pseudomorphs after aragonite are not uncommon.
    Calcite is truly one of the best collection type minerals. There are lots of interesting forms and varieties as well as colorful and beautiful specimens to collect. It is generally easy to identify using its rhomohedral cleavage, reaction to acid and double refraction and makes for a great classroom example of these properties. If it is not the significant mineral on a specimen, it might be an accessory to other wonderful minerals and only enhancing their attractiveness. With its many different forms, environments, associations and colors, a collector could never have all possible combinations of calcite covered.

    • Color is extremely variable but generally white or colorless or with light shades of yellow, orange, blue, pink, red, brown, green, black and gray. Occasionally iridescent.
    • Luster is vitreous to resinous to dull in massive forms.
    • Transparency: Crystals are transparent to translucent.
    • Crystal System is trigonal; bar 3 2/m
    • Crystal Habits are extremely variable with almost any trigonal form possible. Common among calcite crystals are the scalenohedron, rhombohedron, hexagonal prism, and pinacoid. Combinations of these and over three hundred other forms can make a multitude of crystal shapes, but always trigonal or pseudo-hexagonal. Twinning is often seen and results in crystals with blocky chevrons, right angled prisms, heart shapes or dipyramidal shapes. A notch in the middle of a doubly terminated scalenohedron is a sure sign of a twinned crystal. lamellar twinning also seen resulting in striated cleavage surfaces. Pseudomorphs after many minerals are known, but easily identified as calcite. Also massive, fibrous, concretionary, stalactitic, nodular, oolitic, stellate, dendritic, granular, layered, etc. etc.
     
  15. Gustav

    Gustav Thread Starter

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    Thanks man. Now the question of where do I find calcite? I don't think my local Dischem stocks that
     
  16. Perky Pets

    Perky Pets Sponsor

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    I was looking at importing Aragonite, and i found most of these minerals are braught in for the building industry as a cement aggregate...

    Try places like sica or consol.

    As interesting as all this is to get somthing nice and cheap and diferent, if i were you i would just go Buy a small bag of araganite and add a good supliment to the tank.

    My tankis not much bigger than yours, go onto my pics of :Old P.E Boy" and check it out.

    Good luck
    :wave2:
     
    Last edited by a moderator: 11 Sep 2010
  17. Gustav

    Gustav Thread Starter

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    The substrate I have in at the moment is a mix of crushed coral and aragregate. Should I buy some more and add some or remove all my sand and just put in aragregate?
     
  18. Perky Pets

    Perky Pets Sponsor

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    I think , it depends on your budget i belive with the shallow beds of gravle we use, aragonite doesnt make a diff , just status to say " i use aragonite", mine is just cranulated coral, and i use the red sea buff and now trying Nano buff... sumthing, pics are there.

    Put some pics on !!!
     
  19. Nemos Janitor

    Nemos Janitor

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