reedman
Well-known member
So the equilibrium is just between what is in solution and what is bound to a solid (sand, rock, mud, etc.). Is that correct?
Phosphate build up
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You cant call the rock a sink Reed as it sheds. the concept of all of this with a BB is that you remove it instead of sinking it. your P and N will always be associated with detrius, extra food and waste, so you remove it right away and skip the vast majority of processing. Also when you export the above you are taking all the bacteria (organic forms of p and n) that are assc.
both systems (bb and sand/mud) are designed to deal with the above, one chooses to remove it directly and the other chooses to compost it.
Mike
cheeks69
Well-known member
Pardon my ignorance but how do you subscribe to the thread ? This stuff is way over my head but I find the little I understand fascinating.
Witfull
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top of page by first thread, thread tools...subscribe
cheeks69
Well-known member
Thanx Wit ! Got to get used to RF's intricacies 
Ok...I'm glad I'm sparking some thought.
Nikki you're welcome. I'm enjoying it. Also, right now, what you are saying is correct. I want to leave the biology completely out of it for now. I am trying to lay down some basic tools we can use to understand the biology as we go forward, which is really the important part. For right now...I just want to look at the chemistry. For the next few discussions, I will assume that the substrate (be it rocks, sand, mud or whatever) is completely sterile and has always been that way and will never grow any creatures. That way, we focus only on the chemical processes. Keep in mind though that biology is really chemistry. Everything in biology works through chemistry and it all centers around equilibrium. Unfortunately for us, the systems are very complicated and interrelated so the equilibriums sometimes take more complex roles than we are discussing now as I'm sure you are aware. As I think we either know now or will see as the discussion progresses, it is the biology that causes the problems, not the chemistry. I have shown that the chemical processes can be caused to equilibrate and manage quite easily by water changes alone. That is not true with the bio-sink. However, let's reserve that for later.
As far as how soon the equilibrium is reached it depends. In the simple example of water in a jar with sand and Pi, it is reached virtually immediately, or within a few seconds anyway. In this case, it simply depends upon the binding constant and how much Pi we put into the water. In a dynamic system like our aquariums (no biologics though. remember we're sterile now), where we have input sources, chemical aequilibrium and export sources, it will depend. It depends upon:
A) How fast we are adding Pi to the system
B) How strong the binding constant is and
C) How fast we are taking Pi out of the system through export.
In the examples in the plots, which are not that accurate as I did not take the time to get real values for the parameters I used, it takes several months. This is probably pretty fair, however, whether it is 2 months or 15 months who knows. If you want, I can send you the spreadsheet and you can put in more accurate variables if you want. However since the model doesn't take biologics into account it is mainly just a conceptual tool.
Reedman...just because you are adding Pi, doesn't mean it HAS to come out. It will only come out if you have an export mechanism. Exactly what that mechanism needs to be can vary and opinions vary. In our clean system now with no biologics, we are just using water changes to remove Pi and Top off Water and Food to add it. The equilibrium point is determined by the variables A, B and C above. Since we don't really know those exactly right now and I don't want to take the time to dig them up, I suggest we just settle for understanding that there is an EQ point and that we can make it less by inputing less or taking it out faster. Remember again...we are only taking it out by water changes now and aren't considering biologics.
Dan..very perceptive of you
Reedman again. Since we aren't considering biologics...if we put Pi in, only Pi will come out. The only way it comes out is if we take it out. Elsewise it will increase forever until it becomes saturated and precipitates out.
Mike...a rock is a sink. Rock is very porous and unless completey has its pores clogged or is sealed with epoxy or something (virutually impossible) it will always be in equilibrium with the water. However, it is a weak sink. Once we start getting to biologics, other factors you mention will begin to dominate the limestone/water equilibrium such that it is negligable. I understand how you are using the word sink. I believe you are thinking of it as something that really traps P hard and long. However, I would like for us to think of the word more generally, as something that equilibrates with its surroundings. In this scenario a rock would be a weak sink (category 2) and a biology population would be a strong sink (category 3). Later I will talk about how biologics are really not even an category 3 sink, but a category 4 sink, but for now it is helpful for us the think of it as a category 3.
Sincerley...Collin
Nikki you're welcome. I'm enjoying it. Also, right now, what you are saying is correct. I want to leave the biology completely out of it for now. I am trying to lay down some basic tools we can use to understand the biology as we go forward, which is really the important part. For right now...I just want to look at the chemistry. For the next few discussions, I will assume that the substrate (be it rocks, sand, mud or whatever) is completely sterile and has always been that way and will never grow any creatures. That way, we focus only on the chemical processes. Keep in mind though that biology is really chemistry. Everything in biology works through chemistry and it all centers around equilibrium. Unfortunately for us, the systems are very complicated and interrelated so the equilibriums sometimes take more complex roles than we are discussing now as I'm sure you are aware. As I think we either know now or will see as the discussion progresses, it is the biology that causes the problems, not the chemistry. I have shown that the chemical processes can be caused to equilibrate and manage quite easily by water changes alone. That is not true with the bio-sink. However, let's reserve that for later.
As far as how soon the equilibrium is reached it depends. In the simple example of water in a jar with sand and Pi, it is reached virtually immediately, or within a few seconds anyway. In this case, it simply depends upon the binding constant and how much Pi we put into the water. In a dynamic system like our aquariums (no biologics though. remember we're sterile now), where we have input sources, chemical aequilibrium and export sources, it will depend. It depends upon:
A) How fast we are adding Pi to the system
B) How strong the binding constant is and
C) How fast we are taking Pi out of the system through export.
In the examples in the plots, which are not that accurate as I did not take the time to get real values for the parameters I used, it takes several months. This is probably pretty fair, however, whether it is 2 months or 15 months who knows. If you want, I can send you the spreadsheet and you can put in more accurate variables if you want. However since the model doesn't take biologics into account it is mainly just a conceptual tool.
Reedman...just because you are adding Pi, doesn't mean it HAS to come out. It will only come out if you have an export mechanism. Exactly what that mechanism needs to be can vary and opinions vary. In our clean system now with no biologics, we are just using water changes to remove Pi and Top off Water and Food to add it. The equilibrium point is determined by the variables A, B and C above. Since we don't really know those exactly right now and I don't want to take the time to dig them up, I suggest we just settle for understanding that there is an EQ point and that we can make it less by inputing less or taking it out faster. Remember again...we are only taking it out by water changes now and aren't considering biologics.
Dan..very perceptive of you
Reedman again. Since we aren't considering biologics...if we put Pi in, only Pi will come out. The only way it comes out is if we take it out. Elsewise it will increase forever until it becomes saturated and precipitates out.
Mike...a rock is a sink. Rock is very porous and unless completey has its pores clogged or is sealed with epoxy or something (virutually impossible) it will always be in equilibrium with the water. However, it is a weak sink. Once we start getting to biologics, other factors you mention will begin to dominate the limestone/water equilibrium such that it is negligable. I understand how you are using the word sink. I believe you are thinking of it as something that really traps P hard and long. However, I would like for us to think of the word more generally, as something that equilibrates with its surroundings. In this scenario a rock would be a weak sink (category 2) and a biology population would be a strong sink (category 3). Later I will talk about how biologics are really not even an category 3 sink, but a category 4 sink, but for now it is helpful for us the think of it as a category 3.
Sincerley...Collin
Ok, as I've said, I have a plan. I am trying to lay out a conceptual framework from a technical perspective that we can use as a "toolkit" to better understand some of the complex biological processes that go on in our tank. I have two (or three) more disscussions or examples I would like to lay out and then we can start on biological sinks (I can feel the eagerness!). First though, I am getting ready to illustrate the driving force of the universe, closely tied to the second law of thermodynamics. It is called entropy. Entropy is one of the two fundamental forces that drive all spontaneous processes. I will do this with a question this time since my fingers are getting tired.
Let's go back to the Pi in a jar of water with sand. Binding constant still 0.25 (which isn't real, I just picked it because it is a nice round number). This time though the system is a little more complicated. Suppose we have TWO flasks sitting beside each other (flask 1 and flask 2). Between the two flasks is a 1/8 inch piece of tubing with a ball valve that lies below the water level and connects the two flasks such that water can mix passively between the two. We will put 100 ml of water into each flask and 10 grams of sand into each, just like before. Then we will close the ball valve so that NO water between the two flasks can mix. Into flask 1 we put our 1 gram of Pi and nothing into flask 2. Now we know from the example before that with a binding constant of 0.25 we will partition 0.20 grams to the sand and 0.80 to the water in flask 1. Flask 2 now contains only sand and water though with no Pi because the ball valve is closed. Now, we open the ball valve and come back the next day. What do you suppose we will find? What are the concentrations of the Pi in the sand and water in both flask 1 and flask 2? Why?
Anyone??? Collin
Let's go back to the Pi in a jar of water with sand. Binding constant still 0.25 (which isn't real, I just picked it because it is a nice round number). This time though the system is a little more complicated. Suppose we have TWO flasks sitting beside each other (flask 1 and flask 2). Between the two flasks is a 1/8 inch piece of tubing with a ball valve that lies below the water level and connects the two flasks such that water can mix passively between the two. We will put 100 ml of water into each flask and 10 grams of sand into each, just like before. Then we will close the ball valve so that NO water between the two flasks can mix. Into flask 1 we put our 1 gram of Pi and nothing into flask 2. Now we know from the example before that with a binding constant of 0.25 we will partition 0.20 grams to the sand and 0.80 to the water in flask 1. Flask 2 now contains only sand and water though with no Pi because the ball valve is closed. Now, we open the ball valve and come back the next day. What do you suppose we will find? What are the concentrations of the Pi in the sand and water in both flask 1 and flask 2? Why?
Anyone??? Collin
Ok OK no biology...must.....think....chemistry....only....lol.
Ok with out the biological component. clean argonate is a strong binder/absorbant of Pi. It will draw what ever Pi it can until it reaches its saturation point. At the point of saturation it will be in a state of equalibrium as will both flasks, A certain amount of Pi bound into the sand and an amount of Pi soluable in the water. Pi moles will rapidly transfer from the sand to the water column but the constant will always be the equalibrium.
MIke
Ok with out the biological component. clean argonate is a strong binder/absorbant of Pi. It will draw what ever Pi it can until it reaches its saturation point. At the point of saturation it will be in a state of equalibrium as will both flasks, A certain amount of Pi bound into the sand and an amount of Pi soluable in the water. Pi moles will rapidly transfer from the sand to the water column but the constant will always be the equalibrium.
MIke
mojoreef said:
Nearly but not quite. Let's stay away from the saturation point for now. For these discussions lets assume that we don't have enough Pi in the system to even get close to the saturation point. If we allow the Pi to get near the saturation point, we need to employ some more compicated mathematics call the "Langmuir adsoporption isotherm" model. This takes equilibrium into account in the situation (which we really do or will have if our tank gets to old) that adsoporption is slowed down and evenually stopped as active sites on the adsorbant are used up or filled. You are correct in that this will happen if enough Pi is added. However, until later, let's assume we are way below that point. Also the clean aragonite or calcite is a medium powered adsorbent/binder, not a strong one.
and vice-versa
Exactly right. And I will add that the system will also be in a state of equilibrium well below the saturation point. If fact, the system will aways be in equilibrium, or at least moving toword that point as quickly as it can. The study of a chemical system at equilibrium from a physical standpoint is called thermodynamics. The study of a system approaching equilibrium is called kinetics or dynamics, which deals with how fast a system moves towards EQ if it is pertubed. The specifics of this subject are beyond the scope of our discussion for now. However, the model I built in my previous link, and we are discussing, does take the dynamics into account and can project a time period for the pure chemical system to reach EQ if we give it accurate paramters.
Anway...my questions are still on the table. We need some bold souls here!
Sincerely...Collin
Witfull
Well-known member
the sand and water will have the same ratio in both flasks, the Pi is disolved in the water and the flasks( now one flask due to being joined and open) need to reach EQ. the Pi is drawn in to the flask with less EQ as the other until the sand and water in the one reaches the ratio as the other. if during the EQ process more Pi is pulled to the second flask the process will reverse until EQ is established.
That is right. What this shows is the the system is "dynamic" things will move around according to their need to reach equilibrium. Ok, now imagine the same setup. Instead of putting aragonite into both flasks, lets assume that into one flask we put sand again. Binding constant 0.25. However, into the other flask we put something else that has a much higher binding constant...lets say 1000. We put the Pi into the flask with the sand again and then open the ball valve. Now what will the system look like on the next day...where will the Pi be?
Witfull
Well-known member
whew, glad i remember something,,,,lol...nature abhores a vacuum.
next brave soul...your at bat!
next brave soul...your at bat!
Witfull said:
Yes, it does. I'll go off topic and discuss this for a second just for fun. Somebody asked earlier why does a system have to equilibrate? This is a very interesting question that puzzled some of the greatest minds in history for decades. The answer is that there are two fundamenal driving forces in nature that cause everything that exists to try and reach equilibrium. The two forces are called "Entropy" and "Enthalpy". I'll talk about Enthalpy first. Enthalpy is basically either the release or gain of energy (heat) by a system. It drives process toward or away from equilibrium, but is one end of the teeter-toter that always must be balanced by Entropy. It is easy to think of the enthalpy as a process that always want's a system to be in its very lowest energy state. Things naturally want to lose energy and wind down (I know I do with a beer after a long day). In our model system, enthalpy is lost when a Pi molecule binds to the surface of the substrate. In the water, the Pi is moving all around in all three dimensions, it is vibrating along its bonds and tumbling end over end. These are called the kinetic, vibrational and rotational components of a molecules energy. When the molecule binds to the substrate, it can't move around very fast anymore and it can't tumble end over end. All it can really do is vibrate. So, the energy that the molecule was using to do those things is lost or transfered to the water. Thus energy is given up from the molecules that bind to the substrate. Thus their energy is reduced and they like that. With no other forces in play, all the molecules would finally come to rest laying on the subsrate and giving up their heat to the water.
Now comes the other primary force, Entropy. Entropy is a force that wants to provide a state of the system in which chaos in maximized. Another way to say this is that systems try and occupy a state in which, they have the most available statistical combinations available to them. Imagine we have 10 molecules trapped in flask 1 of our two flask system with the ball valve closed. All 10 molecules are in flask 1. If we imaging the inside of the flask to be divided into 100 small volume units that we can number, the 10 molecules can be put into these "bins" in many different ways. For instance, molecule 1 in bin 5, molecule 2 in bin 100, molecule 3 in bin 57 etc. There are many combinations or different ways that the 10 molecules can go into the 100 volume bins. However, when we open the ball valve, now we have 200 volume bins. Thus the 10 molecules can now have many more combinations or ways to by placed in the bins. Because this state offers more statistical flexibility. The system will drive towards state 2. Likewise if we consider the sand. If the sand has a strong binding constant and the molecules have a choice to be spread out all over the water or packed into the sand, which occupies a much smaller volume, they would rather be spread out all over and bouncing, tumbling and shaking all over the place, because the entropy is higher in this state. However, from an enthalpic perspective they would rather lose thier energy and lie on the sand. Thus equilibrium is established by the balance between enthalpy and entropy. These two forces offset one another and are always balanced at equilibrium. The specific nature of the system dictates the relative balance of these two things, or where the EQ point is at. Anyway...enough rambling.
My questions are still one the table??? Remember too, please feel free to ask any question you find confusing or would like elaboration on! This is a complicated subject and not for the lighthearted.
Sincerely...Collin
NaH2O
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OK - I'll take a stab at it, after my weekend of travels. Because the new binding coefficient is sooo large (compared to 0.25) then my gut tells me that the majority will be bound in the new substrate. However, mathmatically - there wouldn't be much of anything found in the new substrate? When I did the calculation the new binding efficient is 1000, which is the ratio of Pi in the water, to the Pi bound or adsorbed onto the substrate. I was playing around with the new flask as on its own (like the example), to see what would be in the water vs. substrate. Based on this, there would be 0.99999999etc. in the water and 0.00000001 in the substrate. Round those up, and you end up with 1 in the water and 0 in the substrate. When the ball valve is open it would be similar to not having a substrate there?
LOL - I sound like I'm out of my mind.....I apologize to all of my chemistry professors for my embarassing attempt.
LOL - I sound like I'm out of my mind.....I apologize to all of my chemistry professors for my embarassing attempt.
Ok, Nikki your gut is right and that is what I was wanting you to get. I think I actually made a mistake earlier and at one place defined the binding coefficient verbally as the ratio of Pi(water)/Pi(substrate) and then wrote the equation as Pi(lime)/Pi(water). I meant for you to use the second equation, and that is how I've been thinking of it and been illustrating it. In this case, your gut would be right and nearly all the Pi in the system would lie in the subrate in flask 2 with the 1000 binding coefficient. That is what the example was supposed to show. Sorry if I confused you.
Ok..so then what does this mean. It means several things. It means that if we have multiple sinks, that the ones with the strongest binding coefficients are going to overpower the ones with the weaker binding coefficients.
It also shows that Pi (or any other species we are interested in that binds...Cu..organic toxins etc) can and will be pulled from one region to another to establish equilibrium. So for instance if we had a substrate, or some sort of sink, that had really good adsorbant or binding properties in the remote tank and one that was weaker in the main tank, then we can keep higher concentrations of Pi in the remote tank than in the main tank.
Ok..so then what does this mean. It means several things. It means that if we have multiple sinks, that the ones with the strongest binding coefficients are going to overpower the ones with the weaker binding coefficients.
It also shows that Pi (or any other species we are interested in that binds...Cu..organic toxins etc) can and will be pulled from one region to another to establish equilibrium. So for instance if we had a substrate, or some sort of sink, that had really good adsorbant or binding properties in the remote tank and one that was weaker in the main tank, then we can keep higher concentrations of Pi in the remote tank than in the main tank.
Witfull
Well-known member
in the case of the weak Vs strong binding, will EQ still be in play? ie some Pi trying to bind to the .25 sand as well as the water or will the stronger binder literally lock the Pi untill a stronger binder or chemical/biological effect cause release?
NaH2O
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LOL - well, at least my gut was right. I swear, I kept looking at it thinking "no way", figures I would misinterpret.
Hmmm - this is getting interesting. My brain keeps spinning all of the complex issues into it....I'm forcing the biologicals out, but it is difficult.
Great explaining, Collin. GASP! I'm actually enjoying chemistry...Dr. Bodner, if you're out there, chemistry is fun, and applicable to my life!
Hmmm - this is getting interesting. My brain keeps spinning all of the complex issues into it....I'm forcing the biologicals out, but it is difficult.
Great explaining, Collin. GASP! I'm actually enjoying chemistry...Dr. Bodner, if you're out there, chemistry is fun, and applicable to my life!
Ok, so on to the next phase. I think we should start talking about biologics now. So we have a nice clean tank with fresh substrate in it...maybe a remote tank too. There is a high concentration of Pi in the sand beds and rocks so what happens? Algea and bacteria like to eat Pi so they grow obviously. How does this affect our equilibrium? What is going to happen to the Pi? Will we still have an equilibrium, or a new sort of equilibrium? How will the Pi react? Now I know we have other sorts of food in a new tank like ammonia and nitrite etc. Lets just stick to Pi now and pretent that Pi is all they need and limit the scope of the discussion.
More questions??
Collin
More questions??
Collin
Well the biologics changes the whole dynamic. The equalibrium now has to encompass the biologicals and the biologicals will dominate. It also really makes the whole equation very difficult as it introduces many many variables. Thier, thiers an easy start for ya.
lol
Mike
lol
Mike
NaH2O
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Algae and bacteria take up the Pi, so that the equilibrium is no longer. The substrate and water will need to balance it out and try to get to equilibrium again. If we figure no more algae and bacteria will feed, then it will get to equilibrium again, but really, the algae and bacteria will keep growing and taking in more Pi, which causes the Pi in water and substrate to keep adjusting until it is used up. (Pretending no die off and releasing of nutrients back into system)
