wouldn't the fact that live rock becomes covered with coralline algea and various encrusting corals effect the efficiency of the live rock. I was thinking that since bacteria live deep within the holes and pores found on the rock, once they are covered over with coralline algea, corals etc, the rock would be loosing some of its effect on keeping the water safe for marine life.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an alternative browser.
You should upgrade or use an alternative browser.
live rock efficiency
- Thread starter fireblade
- Start date
I've seen discussions about this online in the past and I doubt there's really a definitive answer...
My guess is that on a microscopic level, even the coralline would still be a relatively rough surface and provide lots of area for bacteria to colonize. Also, I doubt you could ever completely seal the porosity of the rock with external encrusting growths.
I'll move this to the GRD forum where you'll probably get more feedback.
My guess is that on a microscopic level, even the coralline would still be a relatively rough surface and provide lots of area for bacteria to colonize. Also, I doubt you could ever completely seal the porosity of the rock with external encrusting growths.
I'll move this to the GRD forum where you'll probably get more feedback.
We still don't really know that much about how the bacteria on and in live rock do their work on the nitrogen cycle.
Many believe that the bacteria populate the porous inner structure of the rock. However, a simple diffusion analysis reveals that with diffusion, you can't get enough water in and out of the rock to adequately filter the surrounding volume. Shimek has proposed that small worms and rock-boring critters are adding to the water transport through the rock, but there are a number of very smart people who have substantial problems with this theory based on the possible volume of water exchanged.
A second theory of live rock filtration is that the nitrifying/denitrifying bacteria are largely located on the rough surface of the rock in thin films. Even if you handle the rock, you're only rubbing the films off of the high points of the rough surface, and the film is quickly re-established when the rock is put back in your tank water.
Still a third variety of explanation on how live rock works is that algae and bacteria on the rock are working together to complete the nitrogen cycle and that there is a relatively shallow "skin" of active rock in which active transport of nutrients between the surface and subsurface participants allows for ideal environments (anoxic regions, etc.) to be maintained within the rock.
Your question is a good one, but for now, the only answer is "we don't know". Corraline algae does appear to plate over the structure it's growing on, but has anyone done an analysis of how much water can diffuse through corraline algae? Perhaps it's more porous than we thought? Perhaps it isn't, but perhaps corraline algae harbors thin films of commensal or mutual bacterial/algae populations on it's surface... Or perhaps you'll come up with an even better explanation than I've been able to throw out there.
Regards,
Ross
Many believe that the bacteria populate the porous inner structure of the rock. However, a simple diffusion analysis reveals that with diffusion, you can't get enough water in and out of the rock to adequately filter the surrounding volume. Shimek has proposed that small worms and rock-boring critters are adding to the water transport through the rock, but there are a number of very smart people who have substantial problems with this theory based on the possible volume of water exchanged.
A second theory of live rock filtration is that the nitrifying/denitrifying bacteria are largely located on the rough surface of the rock in thin films. Even if you handle the rock, you're only rubbing the films off of the high points of the rough surface, and the film is quickly re-established when the rock is put back in your tank water.
Still a third variety of explanation on how live rock works is that algae and bacteria on the rock are working together to complete the nitrogen cycle and that there is a relatively shallow "skin" of active rock in which active transport of nutrients between the surface and subsurface participants allows for ideal environments (anoxic regions, etc.) to be maintained within the rock.
Your question is a good one, but for now, the only answer is "we don't know". Corraline algae does appear to plate over the structure it's growing on, but has anyone done an analysis of how much water can diffuse through corraline algae? Perhaps it's more porous than we thought? Perhaps it isn't, but perhaps corraline algae harbors thin films of commensal or mutual bacterial/algae populations on it's surface... Or perhaps you'll come up with an even better explanation than I've been able to throw out there.
Regards,
Ross
Good question, and great answer Ross.
Just how it's working is still up for debate. About the coraline issue however, the only thing I would add is that just about all live rock is already covered with coraline algae when you get it. Some live rock is encrusted up to 1/4" think or more. This, coupled with the fact that we've been using it to filter the water very effectively for many years now leads me to believe that coraline algae has zero negative effect, whatever the final mechanism is.
Jim
Just how it's working is still up for debate. About the coraline issue however, the only thing I would add is that just about all live rock is already covered with coraline algae when you get it. Some live rock is encrusted up to 1/4" think or more. This, coupled with the fact that we've been using it to filter the water very effectively for many years now leads me to believe that coraline algae has zero negative effect, whatever the final mechanism is.
Jim
I would think that LR should continue to be effective for any duration of time, but it also does not hurt to replace a small percentage of rock each year with new LR. This will have the added benefit of introducing more biodiversity.
I prefer something like a 3 to 5% Uncurred LR changeover, once or twice a year. Not because I think the rock isn't doing as well, I do it solely to add new microfauna... and other odd hitch-hikers.
I prefer something like a 3 to 5% Uncurred LR changeover, once or twice a year. Not because I think the rock isn't doing as well, I do it solely to add new microfauna... and other odd hitch-hikers.
Thanks for the responses. My understanding was along the lines of Rabagly's first theory. Thinking that maybey 1-2 pounds of rock per gallon (depending on density) was a guidline that took into consideration that eventualy as it becomes covered with algea there would still be enough surface area that dosn't get covered.
BTW I really like the idea of a small,yearly live rock change. Its always exiting to see what new critters arrive on it.
BTW I really like the idea of a small,yearly live rock change. Its always exiting to see what new critters arrive on it.
Put it this way, if you had the minimim live rock requirement for bactereal denitrification in a reef system, you would be shocked at how much rock it is, its like barely a reef, and for most small to medium tanks just one rock is sufficient. Fully stocked reef tanks usually have 10 - 15 times more rock than is required to successfully denitrify the water. Thats why its such ass kicking stuff. 8)
Sponsor Reefs
We're a FREE website, and we exist because of hobbyists like YOU who help us run this community.
Click here to sponsor $10:
