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Phosphate build up

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mojoreef

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Hey Collin, I noticed in another post you said
phosphates etc. WILL NOT build up and that this is folklore only. I will use this as my starting point and try to prove myself wrong. Please help..Sincerely...Collin
tell me your thinking????


Mike
 

cwcross

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Yes, well, first to respond to your other post regarding humic acids and other bio-sinks being where the toxins lie. I believe you are correct, and am going to attempt to lead up to that point. I would bet that they largely end up higher in the food chain...i.e. plants, fish etc, or out the skimmer. However, not to jump the gun. I first want to evaluate a model for sand bed buildup, excluding bio-sinks. I am building a model in excel which should simulate toxin buildup from a qualitative perspective in any sort of sink in an aquarium for which we can assert a binding constant .

As far as my thoughts, I do not think that calcium carbonate will bind ions very well. More likely these ions could be incorporated into the lattice being built by the corals in a true reef. Aragonite, however, is typically dissolving so I doubt this would happen in the rocks and substrate etc.

Humic acids are good chelants and would be expected to bind metal cations, and maybe their anions, also much more effectively. Humic acids however, would possibly not become "saturated" as per the DSB lore as they would be continually developing along with the biological decay process. It is also possible that these acids might break into smaller pieces, via bacterial action or just shear stress, which would be surface active and could be skimmed off and/or incorporated into plants for export. Just musing and idle thought at this point but lets see where it leads? Any comments?

Sincerely...Collin
 

cwcross

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Ok, here is a link to the outputs of my model. The model assumes a 100 gallon aquarium making 15% water changes every month, with a 1 gallon/day top-off water added and 5 milliliters of added food/day. Top off water, salt, and food, all contain a hypothetical toxin. Plots are rendered for different values of the binding constant. Toxins come in by the input sources and go out only via water changes. The first plot is probably reasonable for ions binding to a calcium carbonate matrix. The intermediate or last cases may be more reasonable for binding to humic acids. Keep in mind that the only modeled export mechanism is water changes. Following is the link:

http://home.houston.rr.com/crosspatch/

if anyone is interested in the spreadsheet itself to play with, I would be happy to send it via, e-mail...just PM me. maybe later I will add some other export mechanisms...C
 

mojoreef

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Interesting Collin. I was leaning more to wanting to talk about the P but lets use this thread for metals.
Ok when you are talking about toxic metals I assume you are refering to them as being soluable correct?? See I cant see any of these metals actually getting to the substraight in the first place. In analysing a sandbed it is basically sand swimming in organics, bacteria byproducts (enzynes) and biofilm. In order for a metals to get anywhere close to the sand it must pass through that first. Wth in the bacteria laidened substriaght are bacteria that actively seek to oxidize and reduce all metals except noble metals. Below them are SRB's (sulfide reducing bacteria) and MRB's (metal reducing bacteria) which produce Hydrogen sufide and Ferrious iron through their biological cycles. Both of those agents will reduce or cause to percipatate the metals to particulate forms and once again become searched out by other bacterias to bind them organically.

Mike
 

cwcross

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Yes Mike, understood. I have seen the question many times of diffrent bad actors (could be metals, phosphates, organics etc) binding to calcium carbonate. I agree with you that this is not likely true and don't need any further justification from my perspective. However, what I am attempting to do right now is to outline, from a more fundamental perspective, how binding occurs, and what its time development would look like. In broad strokes, the simple model I developed can be used to qualitatively understand partioning of a water soluble substance and some sort of "sink" which can interact by adsorbing or binding these various species of "bad actors". Let's consider phosphate, or alternatively it could be copper ions, or an organic. Or we could just simply call it the soluble species of interest. At any given time, the species will exist in the water as a soluble particle. The question in my mind now is what happens to it? The answer is that it "partitions" into various and assorted "sinks". Lets just consider for the moment two sinks: biological and non-biological. How will these two classes of sinks partition with the water? Will they build up indefintely and cause some problems, or will they reach an equilibrium level that is either above or below some critical concentration at which we see problems? I suggest we forget about the biological sink for now because, an animal either has a toxic level of contaminate and dies, or it doesn't and lives. I don't think there is much we can do about that other than trying to keep these levels low (which depends upon the other sinks and sources). If the animal is alive and equilibrating with the environment, we can also consider it a sink, but for now maybe we can forget that. Elsewise, the sinks availables to us are either the substrate, rocks or degredation products of biological processes i.e.) humic substances. Each of these sinks will interact in the same fundamental way and partition with the water column. The model I outlined qualitatively looks at the partitioning of these various particles with various sinks. They key factor is to what level will they build up to and will it cause a problem? I have outlined three regimes a soluble particle will lie in when partioning. The first, where it only partitions weakly, can be shown to be limited fairly easily by water changes. The more frequent the water change, the lower will be the equilibrium concentration. The second, where the partioning is intermediate, can also be managed by water changes, even though substantial amounts of the particle will be bound by the sink at any given time. Again, the more frequent the change, the lower will be the equilibrium concentration of the particle in the water, and in the sink. The third is relatively more dangerious, strong partioning to the sink. In this case, it is not feasible or econonical to provide a frequency of water changes that can keep the equilibrium levels in the sinks at a reasonable level. The sinks will continue to adsorb the particles until they are saturated, and then excess will build to higher concentrations in the water column. So the next question is what are the relative binding constants (partition coefficients) with phospate, metals, organics in the two sinks, humic and limestone? I believe, that partioning with the limestone will be very weak. That leads to humic substances? What is the partioning coefficient with humic substances. I am quite sure it will be stronger than with limestone, but by how much? What are the ramifications for this model? Do we get ever increasing populations of bacteria and algea that will at some point overwelm the tank and crash it? Or alternatively, do these process have some sort of feedback that limits the concentrations/populations of the toxins/biologics. If the nature is such that the populations of bacteria and algea want to spiral out of control, can we introduce processes to help enforce an equilibrium at a non-problematical level? I do not know the answers to these questions? Does this make sense? Any thoughts from anyone? My intention here is to introduce more questions than answers.

Sincerely...Collin
 

mojoreef

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However, what I am attempting to do right now is to outline, from a more fundamental perspective, how binding occurs, and what its time development would look like
ok,


Mike
 

cwcross

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thanks...I need some input/feedback though. I'm starting to feel like I'm in a vacume on this thread, except for mike...C
 

Llarian

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cwcross said:
thanks...I need some input/feedback though. I'm starting to feel like I'm in a vacume on this thread, except for mike...C
I think most of us are still trying to wrap our heads around this. =)

-Dylan
 

snobanker

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uhhhhh yeah...... exactly. :shock: I'm just tagging along because I doubt I can think of any intellegant input.... ;) , but trying to learn

Heck, I can't even spell
 

mojoreef

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LOL Stan,

Colin its a tough subject and hard to breakdown. Why dont you go after one particular group. Say like metals, or organics and so one. Give us some examples.


Mike
 

cwcross

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Witfull, possibly from my understanding. I will try to get more specific as I get feedback and more time to get more specific information.

Others, busy night and afternoon. I don't expect everyone to understand. However, if there is a point that you would like clarified, please ask and I will dig in deeper to make more clear. I will post more tomorrow with some examples that may bring it to a more personal level. Also, I am new to this hobby and am learning a new context to apply my skills. What is the scuttlebut on phosphate buildup or OTS?? I need to understand the state of the hobby here. My tank is only 6 months old so I have never personally dealt with these issues...regards...Collin
 

Scooterman

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Even though some of this is cloudy in my mind, it is good information to read & grasp what understanding I can. Phosphate buildup seems to be a big issue probably because of algae problems, of all types of algae's, it seems to vary in cycles depending on your set-up, husbandry, tank age, equipment, feeding & a ton of other factors, if we can narrow down the problems & remove the nasties before algae's can even survive, while still maintaining a healthy environment for your fish & corals.
 

mojoreef

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OTS is really kind of a myth and is usually just user error after a long period of neglect, so not really a concern.
On phosphate build up it is just another natural cycle. For folks that use sedment beds it becomes a concern because the sand sinks it instead of exporting it.
Here are a few ways P becomes a problem in peoples tanks.
> The sand everyone purchases is argonite which is either dry mined or pulled from the ocean. This sand even without biologicals present is saturated with P through natural binding of P to calcum carbonate. So it has reached its saturation/equalibrium point in the wild. Now if pulled from the ocean you get to add all the bacteria and other organics to the mix that dried on it as it went through the processing process. If mined above ground you get to add all of the above plus whatever nutrient runoff that it was exposed to.
So when you add it to your tank it is already saturated with P. The dried up nutrient attached to it get burnt off usually through the cycling process of starting a new tank, so not alot of concern thier. Towards the 1/2 year mark to a year the bed usually has established a a true anaerobic zone at this point. once this happens bacteria and low ph begin to melt the sand in the lower areas. This melting is often refered to by DSB users as the natural buffering capability of the bed, but with the calcium and carbonate you also get the Phosphate that is bound u in thier to. This now supplies the bed with steady and constant rate of P injection, creating bacteria and algae blooms. With the constant additions of P through feedings, additives, SW mixes and so on this cycle (algae to bacteria to algae) continues to get larger and larger as thier is no place for the P to go. eventually you end up with a tank that is skewed for the growth of algae ant for the growth of corals. Hobbist gets tired of dealing with algae blooms all the time and dumps it.


Mike
 

cwcross

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Ok, thanks Mike. This is much as I thought. First, let me say that in my opinion. A refugium with a mud type substrate (I use a particular brand that I think may be designed very well but not to push my decisions onto others). I believe a refugium/with mud is an extremely important part of a good reef setup. More important than a skimmer which I don't use personally. However, more on that later and maybe some of it will become more apparent as the discussion progresses.

Let's think about phosphate. What is it? where does it come from? and what happens to it? Phosphorous itself is simply an element and I won't get technical about that. Suffice it to say that phosphorous will find itself in may different sorts of compounds, all having different properties. Let us just for now, separate this into two broad categories, inorganic and organic. What does this mean? Inorganic means containing no carbon atoms in the molecule. Organic means the phosphorous is incorported into a molecule having a carbon based backbone. For us here, the only really important sorts of organic carbon are those coming from and/or used in biological metabolism and possibly, depending upon how an aquariast runs his tank detergent types of soaps which pollutes most of our water as they are one of the single most prevelent and widely used industrial chemicals ever produced.

Inorganic phosphate is most likely the sort of compound coming in at the fastest rate with our top-off water. Inorganic phosphate in common water sources is typically either what is called orthophosphate or pyrophosphate. Both are structurally very similar and differ mainly in the lenght of the chains. These inorganic phosphates are simply linked chains of PO3 or PO4, depending upon how one thinks about it. Chain lenghts run somewhere between 3 links up to maybe 7 or 8 links...anyway something like that. When we are adding top-off water to our tanks, these compounds (or any other impurities that we have been talking about) will "cycle up". If we never did a water change and there was no algea or skimmers to take them out...they would build up forever. However, they build up until we are taking them out via water changes at an equal rate we are adding them. That is why the curves on the model I showed start small, increase and level off. At first the compounds are building up faster than we are taking them out due to dilution effects of the water already in our aquarium. At some point, the concentration in the water reaches a point where we are taking things out just as fast as we are putting it in. As the curve in the model approaches this point the curve starts to flatten out and finally is level. The concentration at which point this curve flattens out is dictated by the frequency and size of our water changes and also how much of it can go into a sink. Anyway...so with no other acting forces, the inorganic phospate will equilibrate to some equilibrium level after many months. During this time, what else happens? Well, phosphate is used in several vitally important aspects of cellular metabolism and growth. Here are some. DNA and RNA have phosphodiester backbones so all DNA replication uses this for growth. Also, cell walls are made up of phospholipids. Furthermore, our cells prime engergy source are adenosine tri-phosphate (ATP) and some other important pre-cursers such as NADP. So, cells need phosphate to grow and have energy. Thus, bacteria and other living creatures need a constant source of phosphate. So, this inorganic phosphate and organic phosphates get eaten!. They then branch into many sorts of organic phosphorous compounds and represent a sort of "bio-sink". Think of it as inorganic and organic phosphate coming in and organic phosphate coming out. This is then re-cycled over and over again. If we don't export any of these compounds, then we will get ever increasing amounts of food and bacterial and algea populations will continue to grow as more phosphate enters the system. This is where export mechanisms come in. Our primary export mechanisms are water changes, skimming and biological export via taking algea out of our refugiums. Water changes represent merely a dilution process. Skimming will take out any surface active forms of phosphorous such as phospho-lipids and nuclear material such as DNA and RNA. Refugiums will do all of the above. The algea eats the phosphorous, grows, and then we take it out. My belief is that the refugium is the most important aspect of all the export mechanisms concerning phosphorous compounds. My tank for instance, has no algea that is not well controlled by my cleanup crew. However, my refugium and return duct are filled with hair algea and culerpa. I take it out on an as needed basis and export phosphorous each time I do. Algea will use the widest variety of phosphate sources, whereas skimming will only take out the surface active ones. Anyway, my belief is that, and I hope I have showed why I think so, the refugium will keep phosphorous at a low equilibrium level by acting as a category 3 sink, which can be managed by removal, and thus keep concentrations in the water very low. This aspect is independent of any other impurities dealing with what type of substrate we keep in there. I'll talk more about the substrate as it pertains to the disscussion above later. Questions?? Comments??? Needed clarifications??

Sincerely...Collin
 

aquariumdebacle

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Caulerpa should be used with exteme caution! Mike didn't you say that you had a remote sandbed initially but removed it do to it becoming a nutrient sink? This might be an answer but instead of using sand, use the finer silts (muds) and use a more friendly algae or cyanobacteria.
 

cwcross

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aquariumdebacle. Each and every technique has pro's and con's and there are many ways to skin a cat. However, a remote sand bed is intended to become a nutrient sink. In fact, that is exactly what we want. The problem can come in that any sink has a limit. If we consider a sink to be made up of "active sites" that can host or adsorb a particle...in this case phosphate, eventually, the sink will be saturated and then there are no more active sites to to hold more molecules. At this point we had better crank up our water changes and/or skimmers or the particle will start to build up in the water column at a much increased rate and lead to problems. The other solution is to provide a new export mechanism to keep the sink's active sites refreshed so they can continue to bind particles. For instance, the brand of mud I use suggest to do a 1/2 substrate change out, every other year. As far as timing here, I don't know. I will just trust the manufacturer. However, in principle, this makes perfect sense. By changing out the substrate in the refugium at some frequency, we keep the active sites active and also export the particles being bound by the sink. This is similar to a water change and keeps the substrate fresh. Of course one needs to be careful about doing this so as not to overly disturb populations present in the substrate or realease H2S or somesuch, however, it can easily be done. I could easily incorporate such a substrate export mechnism into my model, which would serve to change a class three sink to having more properties of a class 1 or 2 sink, which is what we want.

As far as finer silts and muds, I think they have a significant benefit. As mike pointed out earlier, calcium carbonate (aragonite) substrates do not bind ions very well, compared to humic substance. Well, a mud is composed of a much greater proportion of humic substances. So I will put forth my belief that a mud is a much more favorable sink for other types of unwanted toxins such as metals, poisonous organics etc. This should help keep these from building up in our water because now we have a class 3 sink for metals etc, instead of a class 1. Furthmore, as we do mud changes, we serve to provide an export mechanism for these problems as well so our animals don't have to deal with them. Now, if I was building a mud from scratch, knowing what I know about chemical kinetics and equilibrium water concentrations of toxins and their binding affinities to various compounds, I would build in some water insoluble and intert ion, exhange resins, possible anionic and cationic amine based polymers or styrene di-vinyl benzene based resins to enhance the binding and capacity of my mud, to provide the tightest binding sink for metals and toxins as I could. This would be easy to do. Then I would go about marketing all its miraculous properties to try and gain market share in this market. However, that is one project I don't have time for now. Maybe existing marketers have already thought of this, who knows. Anyway, even without this, I believe a mud based system would have very desirable properties compared to a sand substrate. I just keep a little of that in my main tank for show.

Sincerely...Collin
 

Scooterman

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MM has been around a while, I haven't heard much bad about the stuff except the fact it must be removed & replaced every so often.
 

NaH2O

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Sorry if my post is skewed all over the place, as I just read the thread and am trying to digest everything that was mentioned. Right now it's clear as Mud ;)

On the point of the remote sandbed/mud bed. I could see this being an effective sink, but only if the detritus and wastes make their way into this area. If they aren't making it into the remote location, the amount of sinking will be limited. Phosphates are a constant input, via additives, food, wastes, etc. Bacteria don't live very long, so when they die the phosphates bound in their tissues will be used by other bacterias or algaes. I am having a difficult time understanding how phosphates can get to equilibrium when it is a constant input? Maybe I misunderstood the model, and it will make sense after my brain finishes processing.

On the point of mud. I know the analysis of miracle mud (using this brand only because the results were published) showed very high levels of iron and aluminum. My understanding is the iron helps the algae to grow, therefore harvesting/exporting nutrients is increased. Would the iron also serve to bind P? (thinking of the ferrous oxide phosphate removers on the market). For aluminum...would the high amount of aluminum present in the mud ever create an issue? I don't mean to bounce the discussion from P to Fe and Al, so you can save this for when you move on.
 
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