Refugiums don't export nutrients?

[brandon429]

I also struggle to see how a bacterial triggering from a little algae die off could compete with daily feeding, and the DOM spikes associated with it. If that was a concern, daily feeding would be bad thorough whatever mechanism a bacterial bloom is bad?

 

I can't edit miss spells on phone lol

[Griever]

No, I am saying that a system without algae will have a lower nutrient system that one with algae.

 

As to the first part, you have to add a "baseball" or large clump of algae at some point correct (to start off)? If you add that to a properly maintained low-nutrient system, you then you will see the algae biomass match the tank and likely die-off to a point and maybe completely. This will trigger the bacterial population and the algae is betting on boosting the bacterial population so that it might free u some inorganic phosphate. So, in that "cullled" regularly scenario, you are still having an active algae releasing organic P byproduct as a result of the Calvin cycle and you also have them excreting glycollate (a carbon source for baceria)... so you are feeding a bacterial mass as well, which algae-removal just can not address. With the Ca based rocks/sand, you have a three-way race of sorts and you have "two sinks". Algae can not get all the P and hold P, the rock will grab some and then the bacteria will process/reprocess back to the algae. It (can) happen in a tight cycled, but here is the trick.... when you have Ca-based rocks and algae in the same system you are banking P in two directions and it also becomes a question of where the bacteria decide to go after their carbon source. So even in a well maintained tank, because you have to keep the P level elevated to keep growing algae, you are also providing the rock ample binding material. You are filling up both of the sinks but only draining one. If bacteria can consume carbon from algae byproducts, it can take less energy that breaking ionic bonds with Ca. This is one reason why many who stop vodka dosing will have an algae bloom on the rocks a few weeks afterwards, the bacteria is switching from the C in the water to the C bound in the rocks and releases P.

 

If you want a nutrient rich tank, then algae-removal can cap the P with reasonable success but remember, you have to keep P high enough for algae. If P is truly limited, the algae would disappear. Algae/ATS mechanisms could potentially work for as long as there was no Ca to bind within a system, but the water would be very high in organics (glycol/Po) .

 

Much of the problem with the "test kits" which are inaccurate for our purposes. We fail to use algae as a bio-indicator to P build-up. Any decent ecologist will tell folks that the presence of increasing algae is a indicator of increasing P.

 

Follow the P... follow it along. It does not stay in the algae, find how/why algae uses the P, find why algae releases the P.

 

People said "look how great my DSB worked" and point to their tanks as an example... and we know that a DSB does not work long for a healthy, low nutrient tank.

 

I understand what you're saying as it applies to an Ultra Low nutrient environment, but you have also said in this thread that this is nearly impossible to keep in this hobby. I still don't see any answers to my questions in your response. I don't doubt that you understand the subject matter, and reef dynamics, but your responses don't seem to really be applicable to reef tanks, which generally have much different nutrient profiles.

[FutureDoc]

PaulB's tank also undergoes massive rebuilding every few years.

 

Here is another "free link" to the cycle of P from NCSU

http://www.water.ncsu.edu/watershedss/info/phos.html

[Reefin Dude]

What I've gathered so far is nobody debates the uptake of organic phosphate because we can test for that. Without decay, any transfer supposedly back and forth between cell and water does not overtake net fixation and benefit in that regard.

 

Its the inorganic phosphate in debate, and we still don't agree on how that will manifest. Pauls 40 year old tank does not factor Pi into his care methods, so it seems that's a nice long term model to show who cares about Pi in a practical sense? I don't need to measure or concern with either phosphate in my old tank...just looking for a helpful summary.

 

it is the water soluble inorganic phosphates that we are able to test for. we are not able to test for organic phosphates. they are bound in all manner of living material.

 

we are pretty sure how water soluble inorganic phosphates will manifest. it is going to be used by algae, bacteria, and some being bound to the calcium carbonate matrix.

 

have you read Pual's maintenance schedule, or talked to him. he absolutely believes in removing the detritus. a few times a year he stirs up his substrate completely then removes as much of the floating detritus as possible. every 10 years or so he takes out the plates and removes all of the detritus that has accumulated under it. he understands that one must clean up after their pets. the corals he keeps are more eutrophic, so the time frame for his cleaning session can be extended more than someone who wants to keep an oligotrophic system. have you seen the pics from his latest cleaning session. i think he called it a private "hurricane".

 

G~

[brandon429]

I didnt see the algae liberation model in that link

[FutureDoc]

I understand what you're saying as it applies to an Ultra Low nutrient environment, but you have also said in this thread that this is nearly impossible to keep in this hobby. I still don't see any answers to my questions in your response. I don't doubt that you understand the subject matter, and reef dynamics, but your responses don't seem to really be applicable to reef tanks, which generally have much different nutrient profiles.

 

I have not said it is impossible to keep a ULN system. I say it is difficult (accounting for a wide arrage of skill types, so more advanced folks will find it easier than noobs) and require good husbandry...I just said that it is impossible to keep a LN or ULN system with a massive algae population present in the sump (or the tank) because the presence of algae is a bio-indicator of high nutrients. It is a fallacy by definition. Algae as a bio-indicator: http://www.sciencedirect.com/science/article/pii/S092752150380139X

 

I have been in this hobby for nearly 10 years, I follow the science (ie biochemistry & ecology). I do not subscribe to "hobbyist theories" that run counter to scholarly evidence to the contrary. Folks can dose their tanks with sodium chloride (ie two-part) thinking that the tank will just deal with the Ca and Carbonate and forget about the rest. I following thing beyond their immediate assumptions. Yes, tanks need to import less than or equal to their export in or to remain heathly, and remving algae can cause a new drop in P.... but you have to allow P to increase in a system in order for algae to even exist, increase the biomass (and the bacterial biomass) and so one is sinking nutrients into a system just to remove some nutrients. It is like squirting clean plates with ketchup and then placing them in a dishwasher with one used/dirty plate so you can run a full load of dishes. Logically algae does not add up for a low nutrient system. The claims of "reduced" P by point at water testing is completely erroneous, the P is in the system and it is undergoing a full cycle... one is just waiting for it to reach one stage before removing some of it.

[brandon429]

yes Ive seen his links. the time he gets in between mass cleanings is longer than most tanks so it seems ok...I saw you guys battle too at rc lol

[FutureDoc]

yes Ive seen his links. the time he gets in between mass cleanings is longer than most tanks so it seems ok...I saw you guys battle too at rc lol

 

I am not active on RC, not since about 2008. I am unaware of G being active on RC.

[xerophyte_nyc]

This thread is a lot of fun. It forces some of us to think more critically, which is a good thing. Nobody wants to be wrong, that's human nature. Discussion is good.

 

Back to the idea of the bacteria-P-algae cycle. There is another fatal flaw, not only in this, but with pretty much any line of reasoning that involves life in captivity:

 

In general, we CANNOT duplicate real world conditions in captivity - whether it is a reef, a desert, or a rain forest. It's just not possible. But the more critical follow up is this: in many cases, it is NOT NECESSARY to duplicate reality because many of the things (good and bad) we see in nature do not bear themselves out in captivity. There is so much "white noise" that we often have no clue as to what is really going on. Like dosing without testing first - it's throwing darts.

 

I like horticultural analogies because they are illustrative of concepts, and because they don't involve a reef, it won't be as emotional. Let's look at the soil in pots. Conventional wisdom tells us to get potting soil from the store, throw in some organics (compost, peat moss, etc.), stick in your plant - provide good light, some water, good to go. Just like planting something in the yard. Yet so many people cannot keep anything alive for any length of time, in a pot, or indoors. They blame a myriad of factors - I over-watered, not enough fertilizer, yadda yadda. The reality is that in in real Earth, there is microbiology and drainage. In a pot, conditions fluctuate so wildly compared to Earth, it cannot be duplicated. Potting "soil" does not work. Some plants are so good at tolerating poor conditions that they survive in spite of the caretaker, not because of them. Want better results? Instead, fill a pot with a completely inert substrate, and all of a sudden moisture is more easily controlled, and nutrition is more predictable by directly offering inorganic N, P, K and other elements. Can't rely on bacteria in a pot to convert organic into inorganic.

 

This shows how nature need not be duplicated, in fact it is detrimental, in this example. But once we understand the hows and whys, we can manipulate the environment, in this case a pot, to achieve an outcome. An aquarium is no different. We just don't yet understand all the hows and whys. What we do is manipulate things. We've gotten pretty good at some aspects: we are making progress with lighting, we are pretty good at providing good flow and good artificial SW, we have different ways to remove harmful waste, etc. I don't think we have yet to really grasp how the cycles, pathways and bacteria in an aquarium work together. Using a real reef is a good starting point, but there's no way it can be extrapolated well to our hobby. Proportions of everything are so different in a tank vs. the ocean.

 

Back to the algae-P-bacteria cycle. Science can demonstrate that in a real reef environment, this may be an important part of the biology. But our aquaria are so far removed from real life that it takes a lot more to demonstrate how that cycle fits in our hobby. I'm not by any means saying that it is not important, I'm just saying I don't think we know enough yet.

 

We know that a eutrophic condition is bad for coral on a reef. In an aquarium, once the hobby has a good understanding of the various "cycles" we then need to figure out how to manipulate the environment for our benefit. For the algae-P-bacteria cycle, we need to show how much Po is released by algae, and what type of bacterial population there really is processing all of this. These findings may be so different from real life that they are irrelevant, or so much more amplified in captivity that they are critical.

 

An ATS or a big fuge with lots of algae are not "natural", but there are enough real-life aquaria using these methods to some degree that they cannot be discounted just because they do not fit into a preconceived model of the real-life reef or ocean. An ATS is simply an extreme example of manipulation in captivity, where flow and lighting are optimized way beyond "natural". I am using one, and will be happy to report my long term results, for better or for worse. The DSB is another concept with questionable merit. I had one for a solid 18 months before my tank crashed - but it was the power outage from Hurricane Sandy, not the DSB. After 18 months I did not experience any visible/ testable negative effects. I'm not saying it works or doesn't work long term. All I can say is that for 18 months it did...and I'm doing it again in my new build.

 

Why am I spending so much time on this? Back to work

 

x

[Reefin Dude]

i am on RC occasionally to see what the current theories of nutrient exports are on RC to see if anything has changed.

 

G~

[brandon429]

no it was reefin dudes battle lol

[xerophyte_nyc]

i said that if the algae is growing, then the water column is high enough in water soluble phosphates to support it.

 

Nobody is disputing this. When we feed the reef with prepared food, it is mostly Po. I understand that ideally, we would need to strip the water column of excess Po before it gets to the bacteria. Skimmers do this, but not very efficiently. Bacteria take care of the rest, converting it into Pi, and some of this Pi bonds to rock, and some is used by algae.

 

What we need to figure out, besides how to best remove the Po that we input, is also how to export the subsequent Pi. Does algae do this quicker than GFO, or water change, or siphoning, or not? Maybe it doesn't matter because equilibrium is reached too quickly? How quickly does it bind to rock? Shouldn't Pi bound to rock also be in an equilibrium state with the water column? If you instantly stripped the water of Pi, won't some dissolve right back into solution without bacterial influence?

 

It seems to me that as long as you keep on exporting P by some means, a tank should reach a steady state. Export needs to be more efficient than binding to Ca or else there will come a time that all this bound Pi goes back into the water column. These things can probably happen rather quickly.

 

We have to constantly monitor our tanks. When we start to see algae in the DT, it could mean that either we are feeding so much that bacteria are busy dumping plenty of Pi into the water column...or that Pi is so low that it is being leached from rock. Macro in a fuge or ATS can help to intercept this excess Pi until a better steady state is reached.

 

Now this gets me thinking - how can we figure out where the Pi is coming from? Too much Po initially, or leaching, or both? How can we manipulate these bacteria in our favor? Maybe we should do monthly drips of lanthanum to strip the rock of bound Pi before saturation occurs???

 

The reason we are having this problem to begin with is because we have to feed a lot in tiny volumes of water, compared to a real reef.

[FutureDoc]

This thread is a lot of fun. It forces some of us to think more critically, which is a good thing. Nobody wants to be wrong, that's human nature. Discussion is good.

 

Back to the idea of the bacteria-P-algae cycle. There is another fatal flaw, not only in this, but with pretty much any line of reasoning that involves life in captivity:

 

In general, we CANNOT duplicate real world conditions in captivity - whether it is a reef, a desert, or a rain forest. It's just not possible. But the more critical follow up is this: in many cases, it is NOT NECESSARY to duplicate reality because many of the things (good and bad) we see in nature do not bear themselves out in captivity. There is so much "white noise" that we often have no clue as to what is really going on. Like dosing without testing first - it's throwing darts.

 

I like horticultural analogies because they are illustrative of concepts, and because they don't involve a reef, it won't be as emotional. Let's look at the soil in pots. Conventional wisdom tells us to get potting soil from the store, throw in some organics (compost, peat moss, etc.), stick in your plant - provide good light, some water, good to go. Just like planting something in the yard. Yet so many people cannot keep anything alive for any length of time, in a pot, or indoors. They blame a myriad of factors - I over-watered, not enough fertilizer, yadda yadda. The reality is that in in real Earth, there is microbiology and drainage. In a pot, conditions fluctuate so wildly compared to Earth, it cannot be duplicated. Potting "soil" does not work. Some plants are so good at tolerating poor conditions that they survive in spite of the caretaker, not because of them. Want better results? Instead, fill a pot with a completely inert substrate, and all of a sudden moisture is more easily controlled, and nutrition is more predictable by directly offering inorganic N, P, K and other elements. Can't rely on bacteria in a pot to convert organic into inorganic.

 

This shows how nature need not be duplicated, in fact it is detrimental, in this example. But once we understand the hows and whys, we can manipulate the environment, in this case a pot, to achieve an outcome. An aquarium is no different. We just don't yet understand all the hows and whys. What we do is manipulate things. We've gotten pretty good at some aspects: we are making progress with lighting, we are pretty good at providing good flow and good artificial SW, we have different ways to remove harmful waste, etc. I don't think we have yet to really grasp how the cycles, pathways and bacteria in an aquarium work together. Using a real reef is a good starting point, but there's no way it can be extrapolated well to our hobby. Proportions of everything are so different in a tank vs. the ocean.

 

Back to the algae-P-bacteria cycle. Science can demonstrate that in a real reef environment, this may be an important part of the biology. But our aquaria are so far removed from real life that it takes a lot more to demonstrate how that cycle fits in our hobby. I'm not by any means saying that it is not important, I'm just saying I don't think we know enough yet.

 

We know that a eutrophic condition is bad for coral on a reef. In an aquarium, once the hobby has a good understanding of the various "cycles" we then need to figure out how to manipulate the environment for our benefit. For the algae-P-bacteria cycle, we need to show how much Po is released by algae, and what type of bacterial population there really is processing all of this. These findings may be so different from real life that they are irrelevant, or so much more amplified in captivity that they are critical.

 

An ATS or a big fuge with lots of algae are not "natural", but there are enough real-life aquaria using these methods to some degree that they cannot be discounted just because they do not fit into a preconceived model of the real-life reef or ocean. An ATS is simply an extreme example of manipulation in captivity, where flow and lighting are optimized way beyond "natural". I am using one, and will be happy to report my long term results, for better or for worse. The DSB is another concept with questionable merit. I had one for a solid 18 months before my tank crashed - but it was the power outage from Hurricane Sandy, not the DSB. After 18 months I did not experience any visible/ testable negative effects. I'm not saying it works or doesn't work long term. All I can say is that for 18 months it did...and I'm doing it again in my new build.

 

Why am I spending so much time on this? Back to work

 

x

 

Actually be must strive to replicate real world condition (and not just the water column, the whole system... see systems approach) but we have to play by the same ecoloical and biochemical rules. P will undergo the same cycling-processes within the biota in the wild as it does in our tanks. We just can not use the same "methods" as abyssal settling and tectonic uplifting are closed to us... the best way to get that is the siphoning. Just like reservoir management, any bio-chemical process that happen in a natural lake can happen in the reservoir but anything that can happen in a reservoir does not always happen in a natural lake.

[FutureDoc]

A goodie if you have access...

A model of phosphorus cycling in the epilimnion of oligotrophic and mesotrophic lakes

F. Chen, W.D. Taylor / Ecological Modelling 222 (2011) 1103–1111

 

My favorite line "Our model is unique in that it uses P as a currency" p. 1109

[xerophyte_nyc]

I just said that it is impossible to keep a LN or ULN system with a massive algae population present in the sump (or the tank) because the presence of algae is a bio-indicator of high nutrients. It is a fallacy by definition. Algae as a bio-indicator: http://www.sciencedirect.com/science/article/pii/S092752150380139X

 

Algae is a bio-indicator in the oceans. That's not the same thing as algae being a bio-indicator in a reef tank. 2 completely different systems, it is not a valid comparison. Let's first maintain a tiny polyp on a 2 inch piece of live rock in a 100-g SW tank, then we can begin to make comparisons.

 

My argument is that algae can be manipulated in a reef tank to help reduce P. Yes, we need to minimize Po to begin with. I get that. We all get that. It's just a very difficult thing to do in a reef tank loaded with animals. Compared to the ocean, our tanks are polluted.

 

Somewhere we need quantifiable evidence that the Po that algae add to the water is equal to or greater than the Pi that it assimilates, prior to export - AND - that this Po contributes significantly to the Po we add in food.

 

Who wants to do an experiment?

 

 

 

but you have to allow P to increase in a system in order for algae to even exist, increase the biomass (and the bacterial biomass) and so one is sinking nutrients into a system just to remove some nutrients.

 

But the Po is already there from feeding, we are not purposely dosing Po for algae growth - we are just using the algae to help eliminate some of that Po. There is no good way to feed our tanks and sink the Po at the same time. Every time algae is harvested, there is a net loss in P.

[xerophyte_nyc]

the best way to get that is the siphoning.

 

If we can't measure Po, how do you know that you are removing it with siphoning? How quickly are bacteria processing it? Is it seconds, minutes, hours? If you are using algae growth as an indicator of high nutrients, is it not just as likely that there is Pi leaching into the water, as it is Po driving bacterial Pi formation?

 

Shouldn't an ultra-aggressive Pi export mechanism drive this entire cycle in our favor? Pull out Pi from the water, open up some P binding sites in rock - keep feeding, let the bacteria convert that to Pi, rinse, repeat. Maybe the Po that algae adds to the water column slows this down? Maybe not? Does anyone know? Maybe we need more live rock with more P binding to act as a temporary sink?

 

I am not directing these questions at you, per se...just thinking out loud.

 

There are a lot of different things going on here, how can we use this info to our advantage and improve P export?

 

EDIT: somewhere along the line there was a great post on another forum about dosing Lanthanum chloride. I used this to prep my dry rock prior to aquascaping. Maybe our tanks need a reboot every once in a while using an aggressive lanthanum drip.

[FutureDoc]

Ok, P excretion:

 

Allometric Scaling of Compartmental Fluxes of Phosphorus in Freshwater Algae

Yuan Hua Wen, Alain Vezina and Robert Henry Peters

Page 48 of 45-56

Hint, they were using radioactive P to trace the flows

"-Excretion of P total radioactivity showed a biphasic decline (Fig. 5). The initial excretion of P was very rapid, and 70-80% of the absorbed radioactivity was eliminated within 0.5-2 h. The rates dropped to a plateau in 1-5 h, after which a further 10-23% of the total accumulated counts were lost" (p. 48)

Now, look at a comparison with marine algae, marine algae appears to excrete P

"Our results showed that about half of the P04 taken up was excreted, whereas Kuenzler (1970) found that 20% of fixed P was returned to the aquatic environment by a marine alga, suggesting that freshwater algae may release more P than marine species."

Now, the kicker is that as P increases within a system, the exchange of P increases so I am hunting down Kuenzier's work so see the P concentration... I am wondering if the P levels for his study were closer to natural reefs <0.009 or closer to our tanks as that will affct the excretion rates. Wen &Vezina's P want not limiting thus the 50%+ It also varies on alga type

When I say that P is swapped around in a matter of hours, I am not kidding.

 

 

If we can't measure Po, how do you know that you are removing it with siphoning? How quickly are bacteria processing it? Is it seconds, minutes, hours? If you are using algae growth as an indicator of high nutrients, is it not just as likely that there is Pi leaching into the water, as it is Po driving bacterial Pi formation?

 

 

 

, ALGAE!!!! Algae will tell you about the availability P before any test can. How long can your system go before you have noticeable algae appearing on the glass? It is a really simple and very accurate to know the limiting concentrations of P in a system. Pi really can not "leach" into the water column unless there is bacterial activity. It can't break the Ca bonds on its own and even cellar decay is dependent on bacteria to convert that Po into Pi. Sure, algae can use a little Po in a pinch but it rather let the bacteria do it for the algae.

 

Bacteria are processing DOCs in a range of a few hours depending on all the metabolism factors. Some of the PSU skimmer studies (open access in hobby trade articles) show this effect as bacteria can reduce the DOC in the water column in as little as 1-4 hours. This is why skimmer must process a system fairly quickly to be effective.

[Grape Nuts]

I will take a shot at summing things up the way I see it... If a tank was to be meticulously maintained around the clock with hourly water changes, over-skimming and crew of siphoners on guard ready to suck out any trace of detritus then macroalgae could not survive in such a nutrient free environment. This environment would be ideal for growing SPS and many of the more delicate corals, but if macro was added into the system it would starve and release bad juju upon its death. A realistically maintained tank will have higher but varying nutrient levels that can usually support macros, but usually can not support the more delicate corals at the same time or for very long. Lots of people find a happy balance growing macros with hardier corals. There are always freak tanks that seem to defy science and have yet to be explained.

[Reefin Dude]

why do we need to limit Po? i think this is the heart of the problem. we only need to limit Pi. we want Po, that is what the animals in our system feed on. we want them to be fat and happy from eating the Po. we do not want the algae to be fat and happy because we were not able to remove left over Po before becoming Pi.

 

if the Po is collected in an area of low flow and the Po is able to pile up, it will retard the decomposition of it, giving us more time between physical siphoning of the Po. the lighter stuff of course will have chances to go through the skimmer. it is all about designing the system around a purpose.

 

GFO is like algae, it can only get to the Pi that comes to it. the advantage of lets say an ATS or a "fugue" is that it is designed to accumulate the Po in that area to help the conversion to Pi by the bacteria. GFO has the last chance of actually getting to any Pi. we are creating this environment to grow the algae, for what reason? why not just get rid of the uneaten and waste Po before it can become Pi. you cut the entire chain down to a reasonable, and reproducible manner where we can then fine tune. the more biomass in the system, the more variables and the more guessing we are doing to advance the hobby.

 

G~

[FutureDoc]

Shouldn't an ultra-aggressive Pi export mechanism drive this entire cycle in our favor? Pull out Pi from the water, open up some P binding sites in rock - keep feeding, let the bacteria convert that to Pi, rinse, repeat. Maybe the Po that algae adds to the water column slows this down? Maybe not? Does anyone know? Maybe we need more live rock with more P binding to act as a temporary sink?

 

I am not directing these questions at you, per se...just thinking out loud.

No worries

 

Actually, if you can have an aggressive Po export method, then you would not have the Pi production. Remember, our P import is mostly all organic P. So if you want to disrupt the P cycle, waiting for bacteria to convert Po to Pi is a missed opportunity. For a system looking to curb P, do not let it "split" into two groups, get the P out that is bound in non-algae sources as Po. Minimizing Po/Detritus also minimized the bacterial bio-mass that is able to convert Po to Pi... limit the converters, limit the conversion.

 

Dang it G, beat me to the response... that is what I get for sending Invic an article

[Griever]

But the Po is already there from feeding, we are not purposely dosing Po for algae growth - we are just using the algae to help eliminate some of that Po. There is no good way to feed our tanks and sink the Po at the same time. Every time algae is harvested, there is a net loss in P.

 

This is the part that the anti-fuge people keep avoiding to answer, and was the core of my question which has been quoted several times, but never actually answered. Feeding enough to keep the stock levels in an aquarium happy will always result in a level of nutrients higher than a low nutrient environment, so how does adding a biological mechanism to trap some of those nutrients, including P, negatively impact the system? I have yet to see a single argument against this, only evidence that as a byproduct, algae can release some of the P it absorbs back into the water in another form, but if you stop and think about it for a few minutes, every ounce of algae removed contains an amount of P contained within the cells at that time, which otherwise would be locked in some other form and staying in the tank until it becomes saturated.

 

I don't see the drawback to using algae as a nutrient export, as long as you make sure it's not dieing because you don't have enough nutrients already in the tank to support it.

[Grape Nuts]

This is the part that the anti-fuge people keep avoiding to answer, and was the core of my question which has been quoted several times, but never actually answered. Feeding enough to keep the stock levels in an aquarium happy will always result in a level of nutrients higher than a low nutrient environment, so how does adding a biological mechanism to trap some of those nutrients, including P, negatively impact the system? I have yet to see a single argument against this, only evidence that as a byproduct, algae can release some of the P it absorbs back into the water in another form, but if you stop and think about it for a few minutes, every ounce of algae removed contains an amount of P contained within the cells at that time, which otherwise would be locked in some other form and staying in the tank until it becomes saturated.

 

I don't see the drawback to using algae as a nutrient export, as long as you make sure it's not dieing because you don't have enough nutrients already in the tank to support it.

I think that is the whole point. To not have enough nutrients in the tank to support algae.

[FutureDoc]

This is the part that the anti-fuge people keep avoiding to answer, and was the core of my question which has been quoted several times, but never actually answered. Feeding enough to keep the stock levels in an aquarium happy will always result in a level of nutrients higher than a low nutrient environment, so how does adding a biological mechanism to trap some of those nutrients, including P, negatively impact the system? I have yet to see a single argument against this, only evidence that as a byproduct, algae can release some of the P it absorbs back into the water in another form, but if you stop and think about it for a few minutes, every ounce of algae removed contains an amount of P contained within the cells at that time, which otherwise would be locked in some other form and staying in the tank until it becomes saturated.

 

I don't see the drawback to using algae as a nutrient export, as long as you make sure it's not dieing because you don't have enough nutrients already in the tank to support it.

 

You first assumption is incorrect. Feeding enough to keep stock levels will not always result in higher nutrient environment. This is false. Water changes, siphoning, and skimming can do it, the amount is just dependent on the bioload in order to achieve it. The "pro-algae" folks want you to think that it is a fact that system will climb in nutrients but with the three method suggest otherwise. The other issue is that even with "growing algae, you also have dying algae" Algae excrete when it is alive, algae really "excretes" when it dies. Even growing hetrotrophs shed cells, algae sheds as well but since it is unicellular....

 

No one doubts that the exact moment algae is removed, there is biomass loss and that biomass has proportional CNP loss. The people is that you have to "wait", allow the nutrients to build, convert between Po and Pi, and then remove the algae. If the algae removal was every few hours and removed exactly the same as the biomass increase, then maybe algae would not be as bad. But algae removal bi-weekly, weekly, or every few day just is not keeping up with the P cycle and you are not keeping up with the export tot the total algae and bacterial biomass increase. So even with moments of net loss, you still have a trend toward eutrophication.

[FutureDoc]

Quick question, would you recommend a canister filter for a reef tank?

 

Often this is a "no" because it is labeled as a "nitrate factory" (at least by many in the hobby). The canister gets all clogged with detritus and it (along with bacteria) aid in the conversion of organic waste into nitrate. The issue with the canister filter is that it traps particles and holds them. During this "holding process" that detritus rots and causes nitrate issues correct? Well, canister can be "ok" but they require constant cleaning (daily or better) so that the detritus is removed before it rots. Thus canisters can work but the level of upkeep really is not worth it for most hobbyist.

 

Kinda the same thing is true for algae. It acts as a "phosphate factory". It traps some P, it looses some P into the water column. Along with bacteria, it can really move P around the system. If you cleaned out ALL of the algae each time and frequently, you would not have that P trap/sink/factory.

 

The difference is that the byproduct of the canister is easy to test (nitrate), but the byproduct of algae is no (Po). For both, we can really use either for the "high nutrients is ok" type tanks, but getting them to not be a factory is nearly impossible without the most manic form of hyper husbandry.

[xerophyte_nyc]

why do we need to limit Po? i think this is the heart of the problem. we only need to limit Pi. we want Po, that is what the animals in our system feed on. we want them to be fat and happy from eating the Po. we do not want the algae to be fat and happy because we were not able to remove left over Po before becoming Pi.

 

if the Po is collected in an area of low flow and the Po is able to pile up, it will retard the decomposition of it, giving us more time between physical siphoning of the Po. the lighter stuff of course will have chances to go through the skimmer. it is all about designing the system around a purpose.

 

But it was just stated a few posts prior that bacteria can process all the DOC in a matter of hours, and since a skimmer is not perfect, there will still be a substantial net surplus of Pi. Are we now assuming that there is leftover Po that evades bacteria, and settles somewhere in the tank?