DSB - Dolomite vs. Aragonite (any minerologists??)

[aj77]

Q: Can anyone dissuade me from using Dolomite (sugar-sized) for my DSB? Aragonite is very difficult to come by here, and the LFS wants $49 for 30 lb of Carib-Sea. <img src="graemlins//bah.gif" border="0" alt="[bah]" />
General Information for Aragonite
Chemical Formula: CaCO3
Composition: Molecular Weight = 100.09 gm
Calcium 40.04 % Ca 56.03 % CaO
Carbon 12.00 % C 43.97 % CO2
Oxygen 47.96 % O
______ ______
100.00 % 100.00 % = TOTAL OXIDE
Empirical Formula: Ca(CO3)
General Information for Dolomite
Chemical Formula: CaMg(CO3)2
Composition: Molecular Weight = 184.40 gm
Calcium 21.73 % Ca 30.41 % CaO
Magnesium 13.18 % Mg 21.86 % MgO
Carbon 13.03 % C 47.73 % CO2
Oxygen 52.06 % O
______ ______
100.00 % 100.00 % = TOTAL OXIDE
Empirical Formula: CaMg(CO3)2
I read that Dolomite lacks the porous structure that will allow more bacteria.
Any input will be appreciated.
AJ

 

[fender]

Not an expert or minerologist, but I have heard that while they are chemically similar, Dolomite is not as porous, as you have mentioned, and dolomite does not disolve as easily making it's buffering capability not equal to aragonite. Other than that - it is superior to silicate based sands and should be fine.

 

[mal]

There is no problem using dolomite as a substrate. Here is a thread answered by a chemist on the same subject.
<a href="http://reefcentral.com/vbulletin/showthread.php?s=&threadid=65974" target="_blank">http://reefcentral.com/vbulletin/showthread.php?s=&threadid=65974</a>
The debate that aragonite sand will buffer better is moot. The disloving of substrate is so slow and minute, (not to mention still debatable if it does in fact dissolve) that it has little if any effect on water chemistry.
As long as you get pure, or very close, it'll work fine. I'm using a mix of dolomite and silica / quartz sand in my 140g. Before aragonite sand was widely available dolomite and silica sands were commonly used. The most important factor DSB is the particle or grain size. A mix of small, very small and tiny.
Here is another dolomite thread that I found interesting, this guy actually did some self testing and posted the results and photos.
<a href="http://www.canreef.com/ubb6/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=1&t=000314" target="_blank">http://www.canreef.com/ubb6/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=1&t=000314</a>

 

[k.lee]

Dolomite is too large for a good bacteria population. LS is supposed to be inhabitednby organisms which need very liottle oxygenation. Ie. Sand, and Dolomite is not sand.

 

[mal]

K.Lee,
Actually it's a mix of large particles all the way down to baby powder-like particles. A good mix of different grained particle sizes is what is recommended for sandbeds. What is your definition of sand? Dolomite is almost 60% calcium carbonate and 40% magnesium carbonate. Or roughly so. I would think baby powder is smaller than sugar sand, so wouldn't there be plenty of area for bacteria growth? The bacteria that converts nitrate to nitrogen gas needs low to no oxygen zones, but the upper levels of the sand bed are inhabited by lots of critters that have to have oxygen to survive. mini-brittles, cope's and amphi's, worms etc. etc.

 

[k.lee]

I think do,omite is 10 fold larger than araggfionite.
I've been tryingto maintain (unsuccessfully)( since the mid-80's corals. I picked it up the, an failed, I'm picking it up again.
Before the 8o's i hyad fish, with dolonmite, and UGF (uNDER GEREAVEL FILTRATION) THROYUGH TGHE DOLONMITE,
since then, rteading nomenclature of success I went with live sand, and it it is much finer than dolomite.
IOn my reef attempts in the 80's IO used bare bottom. I did not suicceed fo thje gravel opr sanmd, but the temp, lack of experience,. and you name it.
BUT, I think the sand works. I'[ve heard it, like I herd about wet/dry filters and proteion skimmiong. So, I'll uise the finer sand.
Asd for sixe, the sand ion "Nature's Own" blows oike the wind, easily lifted by a power4head, and except for some pink pieced, maybe 1/10 overall the size of dolomite gravel.
Yes, I used dolomite in saltwater for a long timne.
PS
rIGHT NOW i'VE BVEEN ACCLAMATUING CLEANER SHRIMP FOR 9 HOURS ./ ME DRUNK --IF i was aware it woukld have ben more trapid.
Peace.
lee

 

[k.lee]

Originally posted by mal:
<strong>K.Lee,
Actually it's a mix of large particles all the way down to baby powder-like particles. A good mix of different grained particle sizes is what is recommended for sandbeds. What is your definition of sand? Dolomite is almost 60% calcium carbonate and 40% magnesium carbonate. Or roughly so. I would think baby powder is smaller than sugar sand, so wouldn't there be plenty of area for bacteria growth? The bacteria that converts nitrate to nitrogen gas needs low to no oxygen zones, but the upper levels of the sand bed are inhabited by lots of critters that have to have oxygen to survive. mini-brittles, cope's and amphi's, worms etc. etc.</strong><hr></blockquote>
I dobn't kniow why, but also my GkH is off the scakle aklmost, and accordingly alkalinity, I get like 15 Gkh! (<font size=-4>should be 10</font>)?
Maybe the sand?

 

[k.lee]

bad speliing err . . .

 

[k.lee]

For the poster, I still think the size of the granule is the crucial piece. The argaonite has less water diffussion when used in a "bed". This lets more bacteria grow in a "anaerobic" stasis to convert nitrates to gas.
I could be wrong like my spelling above, it happens. MM live sand.