I'm guessing that the argument that coralline algae ruining LR is based on a recent article by article by Dr. Shimek. I wouldn't put too much stock in that article. I'll discuss that later for those people that are interested.
Regardless, coralline is not impermeable and does not prevent water movement, bacterial movement, or phosphorus adsorption nor can it prevent bacteria from producing the enzyme phosphatase to re-release the phosphates from the CaCO3. I.e. it cannot trap the phosphates in. The reason is that the thalli of coralline fuse together but it isn't a complete fusion. Just because we can't see a pore with a naked eye doesn't mean that a microscopic bateria can't live in it or move through it. Likewise with a water molecule.
Thallus Organization (PS....there are many related links on this link).
Regardless, you could find out from a scientist what the most non-porous surface known to mankind was and put a bunch of it in your tank, you would achieve higher denitrification. The biofilms that the bacteria would create on the greater surface area are thick enough to allow anaerobic processing. There is a biofilm on your front glass right now that is so thin that you can see through it but Nitrate processing is occuring in it.
Assuming that some of the previous posts are based on one of Dr. Ron's recent articles, here are my thoughts.
The article claimed that worms are what move the water through the rock instead of Van der Waals forces. Yes, they do help but they are miniscule in terms of water movement.
Coralline algae blocks the pores and ruins the rock? How are our coralline covered reefs surviving? How big do the holes have to be? A significant part of much of live rock is decades worth of coralline algae deposits on top of coral skeletons. In other words, the rock IS coralline algae. Algae dissolves holes in live rock? I know of rock boring sponges, urchins, clams, and bacteria that dissolve LR but what type of algae creates holes? (I'm not saying there isn't a type...I just don't know which species does this). Most of the pores were from the fact that most of it was created by coral skeletons. Maybe a small portion by a couple of critters....but algae?
He is using data from 1955 when we didn't understand hardly anything regarding reefs. After discussing all of the ancient algae data in the article, how does the algae affect what he is really talking about...Biological filtration? Biological filtration is done by bacteria but why does the article never mention what bacteria really do in LR?
Dr. Ron said:
If a significant amount of algal and worm biomass was killed by the collection and curing process, this material will mostly remain in the rock, where it will rot. Instead of functioning as a biological filter, such rock would contribute to the system's organic load as these rotting materials slowly diffuse out of the rock over a period of several months.
Well at least he said one smart thing. This is why I recommend that people cure their LR in a separate container or if they want a DSB that they wait until the rock has fully cured prior to adding the sand.
To sum it up, I have read that article and I have a few problems with his line of thinking. If what he was saying is true, then I better start buying worms to add to my Granular Activated Carbon to make it work.
Activated carbon is used in the food industry, chemical industry, etc. because there is a method of things getting inside small pores.
Entrainment occurs naturally with both GAC and Live Rock. We like the more porous live rock because of it's increased potential for biofiltration. We like the more porous GAC because of it's increased potential for filtering as well.
Here's the basics on how carbon works and LR functions in a similar manner. A single pound of activated carbon has the surface area equal to 125 acres. Very porous stuff. It has been baked in such a manner as to create all of the different types of pores and surface area.
TRANSPORT PORES---Transport pores are the internal volume of the carbon granule where the graphitic plates are far apart or the cracks and crevices of the particle. The transport pores act as the "highways" for the contaminants to reach the adsorption pores where they are adsorbed. It is important to note that no adsorption takes place in the transport pores. Transport pores are vitally important, as they allow access to the adsorption pores - especially those deeper within the carbon granule.
Basically the bigger holes.
ADSORPTION PORES---Adsorption pores are the internal volume where the graphitic plates are very close together creating a higher energy. Higher energy is important to adsorption because it is the energy that "holds" the contaminant (the carbon "adsorbs" the contaminant). The volume where the graphite plates are far apart and the cracks and crevices make up the transport pores. It is important to note that all adsorption takes place in the adsorption pores and not the transport pores.
Basically the smaller holes.
VAN DER WAALS FORCE---There is a natural attractive force between all things in the universe. Gravity is one of these forces. In adsorption theory, the force between the contaminate and the carbon is the adsorptive force. It technically is a Van der Waals force. It is this attractive force that enables adsorption to occur. The forces are a function of the distance between the two objects. The closer together the objects are, the higher the attractive force is. The higher the attractive force, the higher the "energy" level of the pore space.
Basically, this is how Phosphates are adsorbed onto LR (and into LR). Van der Waals forces are exactly how a protein skimmer works as well.
HOW DOES CARBON BIND THE CONTAMINATE----Once the contaminant enters the carbon granule via the transport pore space, it diffuses into the carbon matrix until it enters the smaller pores where the adsorptive forces begin to take effect. Once it reaches a higher-energy area, it can no longer migrate (or diffuse) because the adsorptive force is stronger than the diffusional force. The contaminant is adsorbed to the carbon surface by the adsorptive forces (the Van der Waals forces). In this state, the contaminant is referred to as the adsorbate.
That's how water and other compounds get into the live rock....not by worms.
