Aragonite vs Dolimite substrate

[Debacle]

Looking to stock a new tank in a short while and looking for substrate. Ran across several threads about a "White Aragonite Reef Sand" located on eBay. Doing a bit more research on the vendor shows a plethora of different thoughts on it. One person states it is dolomite in his opinion, others state that it may be altered aragonite (I believe Randy Holmes-Farley may have actually taken part in that thread 9 yrs ago).

So, lets say it is dolomite. Any ill effects for a SPS reef tank? Again, some say yes, others say no. Some say aragonite is better at buffering, while others say that neither do exceptionally well as the ph point to dissolve is too low to begin with. Im curious to know if its all an old wifes tail, or if aragonite is really better than dolomite for a reef.

 

[Randy Holmes-Farley Verified Community Expert]

I expect it would be fine. I don’t think substrate does that much, chemistry wise, and the worst that would happen is slowly rising magnesium relative to calcium.

 

[Debacle]

Thank you. I'll take your word for it. Seen some say it's fine and others give a definitive oh don't do that!

 

[Randy Holmes-Farley Verified Community Expert]

Thank you. I'll take your word for it. Seen some say it's fine and others give a definitive oh don't do that!

I'm not sure exactly what they would be worried about, except possibly magnesium release. According to this paper, dolomite is substantially less likely to dissolve into seawater than is calcite, and we know that calcite is less likely to dissolve than aragonite. That means that to get any dissolution, either the pH or the alk in the pore water around the sand grains would need to drop substantially lower with dolomite to get any dissolution than with aragonite sand.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/sed.12259

"All three source seawaters used in the simulations (modern, Mississippian and Aptian) at 30°C are supersaturated with respect to calcite, aragonite and dolomite"

 

[alton]

Dolomite brings back the past. In the early 90's fish stores in my area would give you a choice when setting up an aquarium, crushed coral or dolomite for a substrate.

 

[Paul B]

I started my tank with dolomite in the 70s and it still looks the same so if it disolved, I don't notice it.

Dolomite

 

[Kershaw]

Not to hijack. But how dose dolomite do with sand burrowing wrasses and other creatures?

 

[Paul B]

My pistol shrimp make 4' burrows all over the tank, so much that my rocks moved a few inches to the front of the tank and I had to move it back. The wrasses dive right in.
A little past the middle of the video you can see my pair of pistol shrimp in a burrow that goes all over the tank. They need different size gravel to support the roof of the tunnels

 

[Kershaw]

thanks I have been considering dolomite for a while.

My pistol shrimp make 4' burrows all over the tank, so much that my rocks moved a few inches to the front of the tank and I had to move it back. The wrasses dive right in.
A little past the middle of the video you can see my pair of pistol shrimp in a burrow that goes all over the tank. They need different size gravel to support the roof of the tunnels

nks