Black areas inside Live rock are anoxic! Its not the mineral qualities!

samstersam · 01/27/2007, 10:47 AM

From th8is thread here:

http://www.reefcentral.com/forums/sh...readid=1029742

I just thought I'd start another thread on this.
Previously I thought I had "cheap" rock from the lfs because it was denser than the lalo rock i received from liveaquaria.

I also thought it was cheap rock becasue when I chiselled inside the rock, it was BLACK. I thought it was cheap land mineral type rock they dumped in the ocean to let surface life grow, and that the black areas proved that it was cheap rock. People surmised that the color came from the miinerals of the rocik.

Its NOT! Last night, I placed one of the chiseled black rocks in the tank and woke up this morning and found it had turned WHITE!

My guess is that the black anoxic zones became aerobic, since they are now on the surface. and it actually turned the same color as the outside of the rock!

If it were black due to the color of the mineral qualities of the rock, it would not have turned white/tan...

see for yoourself...

Marsfrogie · 01/27/2007, 07:20 PM

That's crazy. I never noticed that any of my rock was black when I cut it, it was all white. Weird...

Cody Ray · 01/27/2007, 07:45 PM

It still could have been minerals and by splitting it was able to leech into the water.

zuzecawi · 01/27/2007, 07:53 PM

Aquacultured rock is cheap?
Darn it, somebody should have said that to the guy who sold me my 200 lbs worth.

FWIW... that "cheap land mineral rock" is actually generally quarried limestone. Oh, yeah, you know, that stuff under the dirt that was formed when the ocean once covered the land? That's it. Bingo. Limestone. Same stuff reefs have at their base. So basically aquacultured rock is just recycled rock... it came from the ocean and now has been returned to the ocean. It does tend to be denser than say indo pacific liverock, because it isn't necessarily made of the bodies of branching corals and the such. But it's colonized with the same bacteria, algaes, corals, macro and micro organisms as anything else that sits in the sea for any lengthy amount of time. Denser, yes, but cheap? Ecologically, perhaps, it's cheap. Because the harvesting of it isn't raping some reef like the previously unchecked harvest of say, fiji live rock, for example. But cheap as in lesser quality?
Everybody has their own opinion. Mine is that I would rather pay for aquacultured over wild because I would rather know that the impact of my hobby is minimal to the well being of the very reefs I'm attempting to recreate. Aquacultured vs. "wild" live rock is an age old debate, and one each person should make for themselves. But I just couldn't resist replying to the assumption that aquacultured rock is "cheap" and inferior.

And no, I'm not trying to pee in your cheerios, and no, I'm not trying to be critical. Just expressing an opinion... we all have one, and we all know what that can smell like!

wlagarde · 01/27/2007, 08:00 PM

Also, if you bury part of a live rock in the sand it will turn black. If you then re-expose the surface it will again turn white.

reefshadow · 01/27/2007, 09:06 PM

Sure, hydrogen sulfide can colonise anoxic areas like that, it's no suprise to me at all. I break up rock all the time to make frag rubble, and find H. sulfide probably 50 % of the time, especially in rock like yours that has boring type bivalves in it. (I see one on the other thread)

If you smelled rotten eggs/sewer gas, it was H. sulfide. FWIW, I never had a prob with it, I just dump the frag rocks back in the prop tank, never did me any harm.

wlagarde · 01/27/2007, 11:00 PM

Actually, it's not the hydrogen sulfide that does the colonization.

reefshadow · 01/27/2007, 11:18 PM

True, yes, but is is a byproduct of the anaerobic bacterias that do.

Randy Holmes-Farley · 01/28/2007, 07:40 AM

I discuss the black areas that can form inside of live rock here:

Hydrogen Sulfide and the Reef Aquarium
http://reefkeeping.com/issues/2005-12/rhf/index.php

specifically here:

http://reefkeeping.com/issues/2005-12/rhf/index.php#12

It is likely from anaerobic areas that cause black metal sulfides to deposit. Here is a picture of wild live rock that I had for many years before breaking it open:

samstersam · 01/28/2007, 10:27 AM

Randy: My question is that the rock you broke apart did not have the area of blackness that mine had. As you can see, my blackness is ALL throughout the rock within a few centimeters below the surface...

When I said cheap rock, i meant not to barrage aquacultured rock, but I meant to say that its rocks that were not handled properly by the LFS.

Randy is it possible to say that a rock of lower quality is one that has larger deposits of hydrogen sulfide? (kind of how a mismanaged DSB can have large areas of blackness, as per your article, when a highly maintained DSB does not have as much)

Funny, but i have a SINGLE rock that is 30 lbs uncured from lalo.
When split down the middle the entire rock was white. No black areas. The rock is also much larger and has more under-surface areas than the rocks I split from the LFS.

Also, if you look at the lalo on the surface, you can CLEARLY see it is much more alive. I touch the rock's surface and i feel things crunching due to my finger pressure. However, if feel the LFS rock, it just feels like ROCK. Its solid feel in my hands.

01/27/2007, 07:45 PM	#3
Cody Ray Registered Member Join Date: Aug 2003 Location: Phoenix, AZ Posts: 5,101	It still could have been minerals and by splitting it was able to leech into the water. __________________ Limit 1 stupid question per day Current Tank Info: Mr. Aqua 7.5g bowfront

01/27/2007, 09:06 PM	#6
reefshadow Registered Member Join Date: Jan 2003 Location: Central Washington Posts: 1,786	Sure, hydrogen sulfide can colonise anoxic areas like that, it's no suprise to me at all. I break up rock all the time to make frag rubble, and find H. sulfide probably 50 % of the time, especially in rock like yours that has boring type bivalves in it. (I see one on the other thread) If you smelled rotten eggs/sewer gas, it was H. sulfide. FWIW, I never had a prob with it, I just dump the frag rocks back in the prop tank, never did me any harm. __________________ All Your Coral Are Belong To Us Current Tank Info: 30 Deep Blue shallow mixed rimless, MP10, Ecoxotic LED's, SCA 301 skimmer.

01/27/2007, 11:18 PM	#8
reefshadow Registered Member Join Date: Jan 2003 Location: Central Washington Posts: 1,786	True, yes, but is is a byproduct of the anaerobic bacterias that do. __________________ All Your Coral Are Belong To Us Current Tank Info: 30 Deep Blue shallow mixed rimless, MP10, Ecoxotic LED's, SCA 301 skimmer.

01/28/2007, 07:40 AM	#9
Randy Holmes-Farley Reef Chemist Join Date: Apr 2001 Location: Arlington, Massachusetts Posts: 86,233	I discuss the black areas that can form inside of live rock here: Hydrogen Sulfide and the Reef Aquarium http://reefkeeping.com/issues/2005-12/rhf/index.php specifically here: http://reefkeeping.com/issues/2005-12/rhf/index.php#12 It is likely from anaerobic areas that cause black metal sulfides to deposit. Here is a picture of wild live rock that I had for many years before breaking it open: __________________ Randy Holmes-Farley Current Tank Info: 120 mixed reef

01/27/2007, 10:47 AM	#1
samstersam Registered Member Join Date: May 2003 Location: NYC Posts: 389	Black areas inside Live rock are anoxic! Its not the mineral qualities! From th8is thread here: http://www.reefcentral.com/forums/sh...readid=1029742 I just thought I'd start another thread on this. Previously I thought I had "cheap" rock from the lfs because it was denser than the lalo rock i received from liveaquaria. I also thought it was cheap rock becasue when I chiselled inside the rock, it was BLACK. I thought it was cheap land mineral type rock they dumped in the ocean to let surface life grow, and that the black areas proved that it was cheap rock. People surmised that the color came from the miinerals of the rocik. Its NOT! Last night, I placed one of the chiseled black rocks in the tank and woke up this morning and found it had turned WHITE! My guess is that the black anoxic zones became aerobic, since they are now on the surface. and it actually turned the same color as the outside of the rock! If it were black due to the color of the mineral qualities of the rock, it would not have turned white/tan... see for yoourself...

01/27/2007, 07:20 PM	#2
Marsfrogie Registered Member Join Date: Oct 2004 Location: MS Gulf Coast Posts: 463	That's crazy. I never noticed that any of my rock was black when I cut it, it was all white. Weird...

01/27/2007, 07:53 PM	#4
zuzecawi Registered Member Join Date: Mar 2006 Location: Salem, OR Posts: 472	Aquacultured rock is cheap? Darn it, somebody should have said that to the guy who sold me my 200 lbs worth. FWIW... that "cheap land mineral rock" is actually generally quarried limestone. Oh, yeah, you know, that stuff under the dirt that was formed when the ocean once covered the land? That's it. Bingo. Limestone. Same stuff reefs have at their base. So basically aquacultured rock is just recycled rock... it came from the ocean and now has been returned to the ocean. It does tend to be denser than say indo pacific liverock, because it isn't necessarily made of the bodies of branching corals and the such. But it's colonized with the same bacteria, algaes, corals, macro and micro organisms as anything else that sits in the sea for any lengthy amount of time. Denser, yes, but cheap? Ecologically, perhaps, it's cheap. Because the harvesting of it isn't raping some reef like the previously unchecked harvest of say, fiji live rock, for example. But cheap as in lesser quality? Everybody has their own opinion. Mine is that I would rather pay for aquacultured over wild because I would rather know that the impact of my hobby is minimal to the well being of the very reefs I'm attempting to recreate. Aquacultured vs. "wild" live rock is an age old debate, and one each person should make for themselves. But I just couldn't resist replying to the assumption that aquacultured rock is "cheap" and inferior. And no, I'm not trying to pee in your cheerios, and no, I'm not trying to be critical. Just expressing an opinion... we all have one, and we all know what that can smell like!

01/27/2007, 08:00 PM	#5
wlagarde Premium Member Join Date: Apr 2003 Posts: 420	Also, if you bury part of a live rock in the sand it will turn black. If you then re-expose the surface it will again turn white.

01/27/2007, 11:00 PM	#7
wlagarde Premium Member Join Date: Apr 2003 Posts: 420	Actually, it's not the hydrogen sulfide that does the colonization.

01/28/2007, 10:27 AM	#10
samstersam Registered Member Join Date: May 2003 Location: NYC Posts: 389	Randy: My question is that the rock you broke apart did not have the area of blackness that mine had. As you can see, my blackness is ALL throughout the rock within a few centimeters below the surface... When I said cheap rock, i meant not to barrage aquacultured rock, but I meant to say that its rocks that were not handled properly by the LFS. Randy is it possible to say that a rock of lower quality is one that has larger deposits of hydrogen sulfide? (kind of how a mismanaged DSB can have large areas of blackness, as per your article, when a highly maintained DSB does not have as much) Funny, but i have a SINGLE rock that is 30 lbs uncured from lalo. When split down the middle the entire rock was white. No black areas. The rock is also much larger and has more under-surface areas than the rocks I split from the LFS. Also, if you look at the lalo on the surface, you can CLEARLY see it is much more alive. I touch the rock's surface and i feel things crunching due to my finger pressure. However, if feel the LFS rock, it just feels like ROCK. Its solid feel in my hands.