recent article - live rock as bio filter

[Ronald]

live rock h20 movement has anyone remembered Bernoulli?

live rock h20 movement has anyone remembered Bernoulli?

Recall flow and pressure relationships described by Bernoulli and used by the Wright bros as well as sailers etc. Flow across the rock particularly perpendicular to the pores will result in net low pressure at the pore orifice and should result in movement of h20 throughout the rock. We are dealing with much more than diffusion here, we have flow! Check out the specifics here and let me know what you think.

Ron A

 

[Ronald]

computerized axial tomography

computerized axial tomography

OK guys I know I am really late to this discussion, but I do have free access to clinical CT and MRI units and could easily image a "live rock" or dead one or even a live coral in a saltwater bath. Resolution isn't that of EM, but the rock stays in tact. I could get .625mm sections at .1mm intervals and display them in 3D and as sections. i could use density threshold techniques to calculate the volume of solid rock vs air or water using standard pixel counting algorithms (or is it algorithma? ) and get a percentage of air vs rock (error rate likely +/-5%). Anybody interested?

Ron A

 

[pwhitby]

Sorry Ronald, I was out of town at a conference.

The imaging sounds like a good idea. PM me and lets talk.

Paul.

 

[lilko]

Hm... My, my... DSB is no longer good, live rock sucks as well... My, my... I think I will start 100% water changes every day tomorrow Or maybe I should change hobby all together!!!

Sorry for my BS, but I am glad to see some brains finally getting into your preachings Dr. rschimek

 

[tdwyatt]

Writing in Marine Pollution Bulletin, the editors decried the decline scientific objectivity. They wrote that, "It is both wrong and dangerous for a scientist to become personally and inflexibly 'attached' to a theory....Becoming inflexibly attached to a theory, whether or not a scientist considers it his or her own, prevents that scientist from thinking of more useful theories." (Chapman & Giddings 1997) As we continue this reexamination, readers should keep the words of Chapman and Giddings in mind. The hobby benefits most by viewing any proposed explanation for inexplicable phenomena with some skepticism. As we will show, despite the author's confidence, his hypothesis is far from proved, and his conclusions far from fact.

Thanks Richard (Harker) this sums up the total experience to date.

 

[spamin76]

I would just like to point out that not all rock is created equal - what is sold as live rock comes from a tremendously large range from the pacific and atlantic - the age and make up of the rock could have significant differences on the rocks supposed ability to filter - ultimately I think there are far too many uncontrollable factors in this experiment to give it much validity in the final outcome - even separate pieces of rock from a small specific geographical area can have different levels of porosity and composition. Some live rock could be useful and some could not but unless you take measurements and reading on every piece of live rock in every holding tank and every aquarium currently set up there is no established control that you are getting even a minorly representative sample - not to mention the rock which is currently being acquacultured in the wild. Ultimately - this seems like a shot in the dark - live rock is not a geologically or even biologically consistent term - marshall rock is not fiji is not carribean is not tongan - and even all marshall is not necessarily alike. It just seems like the scope is too broad to determine anything all that useful from studying the rock. Just a thought though. I am not a micro-biologist - though I do know a thing or two about some aspects of geology.

I certainly understand what you mean that treatment of the rock before it reaches the tank could dramatically effect its potential as a filter.

I am just not sure how useful any eventual conclusions will be from this study even if you can likely establish that the benefits of live rock is largely overstated - I would like to say that I am partially sceptical of claims associated with live rock - so I am sympathetic - but also it makes a tank look much more fabulous - that and some of the creatures from the live rock are astoundingly resillient - I have had rock with significant die off recover tremendous amounts of bio-diversity of even some supposedly fragile sponges, worms, and tunicates over the period of several months. Amazing things have come out of my rock which were not vissibly there when I purchased it and put it in the tank. Some of the rock has been in a tank by itself for sometime so the creatures that survived the shipping process came in on the rock. On a weekly basis I look in my tank and see new things I have never seen before.
Eventually it may conceivably be possible for the live rock to regenerate a certain degree of it's natural bioload if proper conditions are provided which might render it more useful for filtration.
Again, just a thought.

 

[ikinne1]

Intro Bio class

Intro Bio class

You all forget about the meager simplicities!
Recall that ol' coot that instructed you in Biology 101...put aside his talks on the Krebs Cycle and Blastopheres. Remember it's all about the Reynolds Number.
Surface area is the key to reef keepers' problems. Fluidized bed filters had the RIGHT idea, but the wrong reasoning. Live rock is the way to go based on solely the magic number. With cycled live rock and a great skimmer, you are money...($$$)....to use the parlance of our times, Maude Lebowski.
Discard Dr. Skimmer's lengthy articles on salt effectiveness. I know we've better things to do. Email me directly @ ikinne1@lsu.edu for a straight-up answer (i.e. my opinion). I'm more than qualified: 135gallon x 2 : 1- SPS/LPS. 1-dedicated 135gallons to a 13-year-old hermit crab. He deserves it! PS- it isn't dedicated...he shares it with 23 other schoalling fishes.
58g nano cube. 10g nano cube.

 

[lavann]

hi,

i'm new to this forum(not a scientist) and the thread is quite interesting, i did a search on google and found an experiement that was done by the society of petroleum engineers, called the spontaneous water imbibition into diatomite.

here's link
http://ekofisk.stanford.edu/supria/pubsdirectory/spe46211.pdf

from what i can understand they proved that water went into the rock through capillary action, so i guess that it's possible for live rock to do the same.

i think you could replicate the experiment if you had the equipment and substitute diatomite with live rock.

 

[reefhippie]

Maybe corals are the ventricles?

Maybe corals are the ventricles?

I always love it when I stumble into an area that is not thoroughly researched. It leaves room for some crazy ideas! Here's one I thought I'd toss out on the table, based on some well known facts a few wild assumptions.

Everything we know about ocean life is that it's full of teamwork, living things helping other living things in the quest for survival, and a coral reef can be seen as one big living thing, or it can be seen as millions and millions of small living things, not unlike our own neighborhoods.

The "Berlin Method" suggests that live rock is necessary for the health and well being of corals in captivity, based on its ability to "filter", and we know that corals themselves can act as filters.

We know that corals need excellent water quality, low levels of ammonia, nitrites, nitrates, yada yada yada, and high levels of calcium in the wild, so they obviously need these things in our home aquariums. And if they survive only in these conditions in the wild, something is obviously contributing to the quality of the water there.

We also know that high levels of calcium is also benificial to coralline algea growth, so we can effectively say that coralline itself contains contrentated levels of calcium, which is benificial to corals, and help them grow and spread out. Light alone won't do this.

And since corals are porous, could they not be acting as some sort of a ventalation system, a passagway into the center of the rock, not unlike the branches in our lungs? We assume that the corals are "reaching out" for more light, but maybe there's more to it than that.

One interesting point that this article pointed out for me, was the use of glue to attach the coral frags to the live rock. If corals do in fact provide such a passage, an air passage, a nitrogen gas passage, a waste passage, or whatever, it would make sense that the glue would block these passagways, clogging the ventricles, so to speak. Afterall, glue is not a natural coral reef ingredient.

Thank you for the very thought provoking article.

 

[reefhippie]

Going Deeper…

Going Deeperââ"šÂ¬Ã‚¦

I remember reading that it was the photosynthetic bacteria, by and large, that assisted in the nitrogen gas break-down process within the live rock. If this is true, then maybe corals exist because of those photosynthetic organisms desperately trying to survive under the shade of the coralline algae. In other words, corals are the result of photosynthetic organisms and calcium-based algae, as a way of bringing in light, and passing out nitrogen gases. Thus, corals need them, and they need the corals.

So in theory (mine anyway), the coral only knows that it needs sunlight and nutrients to survive, and so in our home aquariums, whether there is glue between itself and the live rock is unimportant because we have expensive protein skimmers and calcium reactors.

 

[mjbock]

Water movment in rocks, reality check

Water movment in rocks, reality check

I have noticed a misconception in the extreme. It would appear as though Dr. Ron proposes that organisms larger than bacteria are the only mechanism for water movement through "live rock". I content that this is likely untrue. Given that water movements inside an aquarium will set up pressure differentials within the tank and therefore on a piece of rock, these pressure differentials provide a motive force. Obviously this assumes that the pores in the live rock are at least to some degree connected. A similar motive force has been found in sediments. As water moves along sand ridges porewater has been demonstrated to migrate through the ridges (I wish I had the reference but I don't remember where I saw it). Thus water migrates through sediments in response to movement in the overlying water. As everyone is so found of pointing out, I do not have direct evidence to support this contention as it applies to live rock but it is a reasonable extrapolation.

In my view all three mechanisms for water movement: advection diffusion, pumping by organisms, and flow induced by pressure differentials are of potential importance. No Dr. Ron, the boundary layer effect is not sufficient to mean there is "no flow at the surface of the rock" think about turbulent eddies etc, as shown in any good fluid dynamic text. The no-slip condition is really only a theoretical construct that approximates observations and breaks down totally in turbulent flow. As we all know, true and complete laminar flow is a rare thing. However, I agree the flow at the boundary is not sufficient for feeding and gas exchange for macrofauna, I have spent many hours watching worms etc in feeding in flow and have published many a paper on the topic.

I must comment this argument triggers memories of the whole "bacteria rule the biochemistry of the ocean" versus bacteria are just food for everything else arguments that permeated by time in graduate school.

 

[jfritter]

Fascinating, although I did not see logic applied in this discussion. If there is denitrifying bacteria on the LR, then they are performing as desired. If they were not, they would not be there.. Their sufficency without the additional surface area of the LR would depend on the bioload and the substrate.