Is it feasible to remove the skimmer? Could it solve the decades-long problem of nutrient accumulation?

[Belgian Anthias]

thet if one does not respect the basics of growthI don't think anyone has come to that conclusions except you.

I still have no idea why you think a skimmer will increase nitrate.

Seriously, is there anyone else reading this thread that accepts the rationale for skimmers to increase nitrate? I don't mean it as a joke or criticism I'm trying to understand what, if anything, I am missing in this whole discussion.

I've asked a few times and get no satisfying explanation.

i am sorry , but I can not explain it any better. I hope others will see the logic and understand.

I try to explain it in a way that everyone can see the logic of it, even for those without the necessary basic knowledge.
A minimum requirement is to know how growth comes about.

Good management starts with what is added as balanced nutrition, it determines what remains later, which cannot be removed by growth will accumulate. This presupposes that what is added can also be effectively used up by growth and not be partially removed leaving a portion of what will be left behind, unusable for growth until the nutritional balance is restored.

With less good management, products and devices will be developed to remove what is left behind and is considered problematic and what should not be there in the first place.
Sometimes resources and measures are advised and used for this that involve much higher risks than the risk represented by what has been left behind due to poor management.

 

[Belgian Anthias]

A problem difficult to solve using a skimmer is , even when using AAM for managing the nutrient balance, exempt for nitrate and phosphate it is unknown what after consumption of the feed may accumulates and what is removed by the skimmer. Each nutrient is toxic and growth-inhibiting at a certain amount including trace elements. Nitrate is toxic only when present at very high levels. if nitrogen may accumulate it normally will show having an increasing nitrate level, but if ammonium may accumulate most will not know and point to nitrate as the culprit when growth is inhibited. Also, if nitrogen may accumulate due to creating a nutrient unbalance also other essentials once present in the food may stay behind of which we do know they may become very toxic but of which we have no idea how much and of what substance is left behind. Sufficient growth will also ensure that these substances are used up in time for the purpose for which they were added.

ZMAS ( zero emission marine aquaculture system) now used for aquaculture of marine shrimp may support 80-120kg bioload/m³ based on a heterotrophic carying capacity using feed with a C/N ratio of + 12 . When the growth rate becomes inefficient everything is harvested. In such systems no or very little nitrate is produced, the water is cleared by heterotrophic growth. TAN is removed fast, fast enough for very sensitive juveniles. In such systems new produced protein ( growth) is reused. A balance is created between consumers and reducers.

If the best skimmer available ( +- 35% removal of TOC and DOC) is used in a ZMAS what will happen?

What about nitrogen knowing shrimp cultured in ZMAS release +90% of all nitrogen consumed, most as ammonia ?
How all that ammonia will be removed with a skimmer in operation? Will total ammonia nitrogen ( TAN) build up or not?
I have no doubt ammonia will reach a toxic level fast , I have explained why. Others may see no problem and may be able to explain why using a skimmer is not a problem for the nutritional balance in the system.
Because a ZMAS is a heterotrophic based system no ore very little autotrophic carying capacity is available. My opinion the effect of the skimmer will be shown by TAN , followed by nitrite production. Before days later some nitrate is produced I think one will smell how the skimmer has influenced growth and combined the accumulation of toxic nitrogenous substances. Why? My opinion because this skimmer has removed +- 35% of the main growth regulation factor present in the feed and released by the shrimp essential for , and removed the balance between consumers and reducers.
It is an extreem example for NOT using a skimmer, but it shows how a skimmer influences the nutrient balance.

In a reef aquarium having a very low bioload, the effect of using a skimmer will build up slowly, but an aquarium is a long term project. The use of commercial food with a very high protein content of + 50% will promote the production of nitrogen and nitrate, speeding up the nitrogen problem. After using a skimmer for a period of time Only regular water changes may prevent possible accumulation of minor nutrients to reach a toxic level, on the assumption that for growth balanced food is used . This can be avoided by matching growth and feed ( not possible using a skimmer).

 

[GARRIGA]

Has anyone tested Purigen as an effective measure to replace the skimmer? If it removes the same impurities then wouldn't it be more effective since it could be used in a reactor which fed by the return pump would insure the water is 100% treated? Not talking about dropping a bag in the sump. Never understood how that remotely close to a reactor or canister filter.

 

[Randy Holmes-Farley]

Has anyone tested Purigen as an effective measure to replace the skimmer? If it removes the same impurities then wouldn't it be more effective since it could be used in a reactor which fed by the return pump would insure the water is 100% treated? Not talking about dropping a bag in the sump. Never understood how that remotely close to a reactor or canister filter.

Purigen removes some types of organics. Likely somewhat different ones than skimming because the principle is different. GAC is similar but also somewhat different. Purigen doesn't export planktonic bacteria or phyto or much particulate detritus like a skimmer does. but maybe some. Doesn't aerate.

But GAC or Purigen or similar polymer binders are certainly desirable in a skimmerless system, and likely in a skimmed one as well. I used GAC and skimming together.

 

[GARRIGA]

Purigen removes some types of organics. Likely somewhat different ones than skimming because the principle is different. GAC is similar but also somewhat different. Purigen doesn't export planktonic bacteria or phyto or much particulate detritus like a skimmer does. but maybe some. Doesn't aerate.

But GAC or Purigen or similar polymer binders are certainly desirable in a skimmerless system, and likely in a skimmed one as well. I used GAC and skimming together.

I don't see issues with bacterial blooms when carbon dosing and I will purposely overdose when I do. It's not an everyday thing for me. Perhaps the large biological media I'm using assists. Perhaps not. Seems logical that having a home might reduce the bloom unless I'm just not grasping exactly what causes it which is likely.

I'm purposely capturing detritus and letting it decompose naturally. Nutrients aren't an issue and expectation was deriving carbon from this and reduce/eliminate carbon dosing. Latter hasn't been the case. Don't know why. Perhaps as it ages this will change.

I too use GAC because I want clear water and Purigen alone has not given me that. Water has remained yellow when just running that. Plus once I add corals, my understanding is that it will remove the chemical warfare I might have.

Aeration is a concern but this tank won't be up for long and I have ideas for the DT. Not 100% convinced that a skimmer for me worth the hassle for the additional benefit in that. It might. Unfortunately, no way of knowing and I've tried finding data confirming it.

Main focus on my experimental tank is completely doing away with a sump and it's components. Looking to have a custom AIO with a larger chamber area to handle a larger biological component with a separate hookup to a canister such as an FX6 to perform chemical and polishing. Keep it simple. Reduced maintenance. Although it will have a controller and dosing with redundant fail safes. Should reduce noise and potential flooding. Why I'm so adamant about going skimmer-less. Not because I don't believe in them but because I know the effort and concessions needed to operate one. Plus money saved on sump/skimmer goes towards better lights. Especially those without fans. I'm seeking tranquility in my approaching age.

 

[Belgian Anthias]

But GAC or Purigen or similar polymer binders are certainly desirable in a skimmerless system, and likely in a skimmed one as well. I used GAC and skimming together.

Only at the end of the filtration chain, otherwise they will have the same side effects as a skimmer and limit the filtration rate ( growth). They all remove organic carbon and other nutrients once part of the for growth balanced feed otherwise used for to support growth able to remove all released nitrogen. inorganic nitrogen and other released inorganic nutrients will be left to accumulate.

If we remove organic carbon from the feed and not enough nitrogen, more nitrate has to be produced to support the carrying capacity, otherwise the system will fail. To remove all nitrogen by growth we need all nutrients once present in the feed.


For the same reason, if one has invested in a skimmer one can use it at the end of the filtration chain, maybe as an aerator.
A skimmer is very unreliable when it comes to estimate the removal rate and grade, one has no clue how much of what it will remove, one can only hope it does what we expect it to do.
As detoxinator and to remove coloration I prefer GAC, we do know what we may expect of GAC.

 

[Garf]

Only at the end of the filtration chain, otherwise they will have the same side effects as a skimmer and limit the filtration rate ( growth). They all remove organic carbon and other nutrients once part of the for growth balanced feed otherwise used for to support growth able to remove all released nitrogen. inorganic nitrogen and other released inorganic nutrients will be left to accumulate.

If we remove organic carbon from the feed and not enough nitrogen, more nitrate has to be produced to support the carrying capacity, otherwise the system will fail. To remove all nitrogen by growth we need all nutrients once present in the feed.


For the same reason, if one has invested in a skimmer one can use it at the end of the filtration chain, maybe as an aerator.
A skimmer is very unreliable when it comes to estimate the removal rate and grade, one has no clue how much of what it will remove, one can only hope it does what we expect it to do.
As detoxinator and to remove coloration I prefer GAC, we do know what we may expect of GAC.

To me this only makes sense if the C to N to P ratios in feed are constant. They are not. They vary wildly.

 

[Belgian Anthias]

I don't see issues with bacterial blooms when carbon dosing and I will purposely overdose when I do. It's not an everyday thing for me. Perhaps the large biological media I'm using assists. Perhaps not. Seems logical that having a home might reduce the bloom unless I'm just not grasping exactly what causes it which is likely.

Bacterial blooms may be very destructive for other life forms, certainly in a small closed environment.
r-strategists, they use up available nutrients and oxygen very fast, and will die at the same logarithmic rate as they have grown.

How a coral may manage its holobiont in a tank where the nutrient availability fluctuates and nutrients are stolen to support very fast useless growth.
It has been shown overdosing of organic carbon may kill corals.

Why dosing organic carbon? To add organic carbon which one has removed using a skimmer? To remove nitrate, safely stored usable nitrogen, or and phosphate, all accumulated for the same reason? If the system has found a certain balance based on the skimmer, even when this balance includes accumulation of nutrients, what may happen when adding carbohydrates?

Basic management of nutrients starts with the feed, with what is added to the system.
Using a skimmer one is NOT able to manage the nitrate production based on the C/N ratio of the feed because one has no idea of how much carbon once present in the feed will be removed by the skimmer.

So, some add Wodka, based on the nitrate level, in an attempt to correct a situation mainly created by basic management. Nitrate is a safely stored and usable nitrogen source, Wodka may kill corals! ref: MB vodka

 

[Belgian Anthias]

To me this only makes sense if the C to N to P ratios in feed are constant. They are not. They vary wildly.

We decide what we add.
The content of different organisms, also of the same species, will and can deviate drastically from what is sometimes called the Redfield ratio. But they all need the basics for growth to start with. The N and P ratio's needed for basic growth do not vary widely. To know the nitrogen content of feed we divide the protein content by 6.25.
The consumption will not follow the general rule. Most organisms store a nutrient reserve, some organisms are specialists storing phosphorus, others nitrogen, others sulfur, iron, etc; Algae will take up more nitrogen in relation to phosphorous in function of availability. Others as cyano will store more phosphorous. They will use what is available and store some of it for later use, it is sometimes species dependent, even clade dependent. Most marine macro algae have a high C/N ratio,

This way the water may be cleared of all nutrients by growth, also if the availability fluctuates. But they can only use what is made available .

Why nitrate may accumulate in a well lit aquarium?

We decide what is fed. All the rest is about competition for what was once added.
If not enough organic carbon is available , nitrate is produced. Adding food of marine origin with a protein content of +- 35 % will lead to normal nitrate production, enough for the producers to restore the balance. The carbon content will determine how much from the feed can be used by fast growing heterotrophs and by slower growing autotrophs including the producers.
In a nitrate producing system part of NO3-N is exported constantly. Most Carbon is used for energy production and released as CO2. All other nutrients stay in the system if not harvested.

A skimmer will remove organic carbon constantly leading to more nitrate production, but will also export some of the nutrients needed to use up the nitrate reserve created .


If marine fish are fed a commercial food having a protein content + 50% this will lead to a very high inorganic nitrogen production. If a skimmer or any other means for removing only organic carbon compounds does what it's supposed to do , then one can be very happy that sufficient nitrification capacity is present to convert the available nitrogen into nitrate. How the nitrate is used up is then a concern for later.

 

[Belgian Anthias]

Does a skimmer prevents nitrate production, as I was told when I bought my first skimmer and have read in the many books I have read regarding the saltwater aquarium?

Or was it based on the same logic as when I was advised to remove my bio because it was responsible for producing nitrate.
The skimmer did what he did for decades, but the advise for removing my bio I never followed .

 

[Belgian Anthias]

The basics of nitrogen management.

In a closed marine live support system + 85% of nitrogen present in feed is released to be reused, most is inorganic ammonia, to become toxic if it may accumulate.

Several different nitrogen pathways are available for the system. Heterotrophic, autotrophic, and photautotrophic
These are dependent upon the availability of carbon and it forms, either as inorganic carbon as alkalinity or organic carbon from the feed and fecal matter. Thus for a recirculating system where all of the solids containing organic carbon are rapidly removed from the system, the system would be primarily autotrophic, utilizing inorganic carbon from the alkalinity as its carbon source. For a zero-exchange system, the solids remain in the production tank and all
of the carbon and nitrogen from the feed and fecal matter are available for heterotrophic bacterial production. Natural food with +- 35% protein largely convert the nitrogen to heterotrophic biomass, some autotrophic conversion occurs, which utilizes inorganic carbon from the alkalinity. (ref: Ebling EnCo 2006)

Most reef aquarium systems export organic solids and DOC and depend on water changes, resulting in a mainly autotrophic system, depending on autotrophic carrying capacity, the nitrification capacity. the production of nitrate consuming alkalinity.

A skimmer removes organics , this way promoting the system to become more autotrophic, the production of nitrate, and the consumption of alkalinity. With a skimmer in use it is not possible to manage the nitrate production based on the C/N ratio of feed.
Nitrate production is not considered a problem, on the contrary.
In a closed re-circulation system nitrate production can be easily adjusted to your liking, and all nitrate can be used by new growth adding alkalinity, this if the nutrients once present in feed can be reused.
A skimmer not only limits heterotrophic ammonia reduction but also photo- autotrophic ammonia and nitrate reduction due to removing not only essential organic carbon but also other essential nutrients which are part of the removed organic matter. The effect on alkalinity is negative both ways , due to favoring nitrification and limiting nitrate consumption.

I did know my bio was not responsible for nitrate accumulation, my bio could not be responsible for exporting essential nutrients. And a bio does export nitrate A skimmer was always used in combination.

Some add for corals dangerous products to correct what should not take place when applying the basic rules for growth, starting with the food source.

Why nitrogen may accumulate in a well lit aquarium?

 

[Randy Holmes-Farley]

Does a skimmer prevents nitrate production, as I was told when I bought my first skimmer and have read in the many books I have read regarding the saltwater aquarium?

Or was it based on the same logic as when I was advised to remove my bio because it was responsible for producing nitrate.
The skimmer did what he did for decades, but the advise for removing my bio I never followed .

I do not know what you are suggesting, but maybe you are just reading the wrong books.

Of course skimmers do not prevent nitrate production from ammonia produced in the tank, nor do they remove nitrate directly. Anyone suggesting otherwise does not understand the chemistry of skimmers. But I do not recall seeing any such claims.

Skimmers WILL remove organics, and that export can (must) reduce the production of nitrate if those organics would otherwise be metabolized in the aquarium.

"Or was it based on the same logic as when I was advised to remove my bio because it was responsible for producing nitrate."

That's not unreasonable advice if you had elevated nitrate, IMO. Many folks who did remove bioballs saw a decline in nitrate for reasons that I think are clearly understood, if not universally recognized by average reefers.

​

 

[Randy Holmes-Farley]

Why nitrogen may accumulate in a well lit aquarium?

More input from foods than consumption by photosynthetic organisms. Doesn't seem complicated to me.

 

[Belgian Anthias]

Skimmers WILL remove organics, and that export can (must) reduce the production of nitrate if those organics would otherwise be metabolized in the aquarium.

"Or was it based on the same logic as when I was advised to remove my bio because it was responsible for producing nitrate."

That's not unreasonable advice if you had elevated nitrate, IMO. Many folks who did remove bioballs saw a decline in nitrate for reasons that I think are clearly understood, if not universally recognized by average reefers.

​

Metabolism comsumes carbon for energy but removes nitrate Each heterotrophic cycle the system will become more autotrophic, if organic carbon is not imported by Photo-autotrophs.

Preventing heterotrophic metabolism in time may result in less nitrate production, if relative less organic carbon and more nitrogen is exported by the skimmer as would be exported by methabolism.
But what if metabolismn is prevented of photo-autoautotrophs and heterotrophs, by removing only part of the nutrients needed leaving the other part to accumulate. How growth may continue to consume produced nitrate?
Is the user of a skimmer guaranteed this is not the case?

if I have to make a choice between nitrate consumption leaving not much behind and nitrate production prevention using a skimmer my choice is made.

Does a skimmer respect the basis of nutrient management!? Nitrate production does NOT depend on the quantity of organics present but on the C/N ratio of those organics. More nitrate is produced if less organic carbon is availble.

Every heterotrophic nutrient cycle the system becomes more autotrophic due to the carbon export, producing more nitrate, To keep the balance it is importend to store as much as possible in growth which can be harvested easily and is able to store everything into growth for a long period of time , adding organic carbon if cycled , preventing the system to become more autotrophic.

The production of phyriphyton is a mix of both, creating a food source with a C/N ratio of +- 10, not resulting in nitrate production. The consumption of macroalgae will provide organic carbon, leading to less nitrate production.

A bio does produce nitrate in funtion of the C/N ratio. A substrate based bio is in the first place a remineralization filter, consuming DOC, producing the elements for growth and nitrate only if not enough organic carbon is available, which normally is the case using natural feed. High protein feed will produce more nitrate. What happens with the produced ammonia if ammonia is not transformed into nitrate?

Most reefsystems use a skimmer and photo-autotrophic growth is limited by removing target nutrients, preventing balanced growth, These systems promote heterotrophic growth turning the system each cycle more and more autotrophic, producing more nitrate in time, nitrate which can not be used up by photo-autotrophic growth due to target removal of some nutrients, being a standard procedure in modern reefkeeping; This instead of preventing those targeted nutrients may accumulate. To achieve this using a skimmer is no help.


A biofilter is NOT responsible for nitrate accumulation as often published.
A skimmer my cause a system to become more autotrophic, needing more nitrate production to support the carrying capacity.

If nitrate accumulates this is not because of using a remineralisation filter, a bio, but because sufficient nitrogen consuption is not available. To much high protein feed to start with. If not enough nitrogen compsumption is avalable I prefere the nitrogen to be nitrate-nitrogen. One may start with adding less nitrogen, by lowering the protein content of the feed.

Using a system based on growth, a biofilter is used, all nitrogen will be consumed, growth is harvested. When adding a skimmer, this is not possible and AAM is made difficult, Using AAM the situation can easily be corrected using for the target nutrient modified feed, supporting growth, the opposite of what a lot of reefers do.


Ammonia is produced, if the system becomes more autotrophic I prefere this nitrogen to be stored in nitrate. Each nutrient cycle the system becomes more autotrophic as each cycle a lot of organic carbon is exported as CO2 for energy. Normally the balance is kept by photo-autotrophic growth which in most modern reeftanks is not the case.

Why nitrate may build up slowly in a well lit aquarium?

 

[Garf]

Metabolism comsumes carbon for energy but removes nitrate Each heterotrophic cycle the system will become more autotrophic, if organic carbon is not imported by Photo-autotrophs.

Preventing heterotrophic metabolism in time may result in less nitrate production, if relative less organic carbon and more nitrogen is exported by the skimmer as would be exported by methabolism.
But what if metabolismn is prevented of photo-autoautotrophs and heterotrophs, by removing only part of the nutrients needed leaving the other part to accumulate. How growth may continue to consume produced nitrate?
Is the user of a skimmer guaranteed this is not the case?

if I have to make a choice between nitrate consumption leaving not much behind and nitrate production prevention using a skimmer my choice is made.

Does a skimmer respect the basis of nutrient management!? Nitrate production does NOT depend on the quantity of organics present but on the C/N ratio of those organics. More nitrate is produced if less organic carbon is availble.

Every heterotrophic nutrient cycle the system becomes more autotrophic due to the carbon export, producing more nitrate, To keep the balance it is importend to store as much as possible in growth which can be harvested easily and is able to store everything into growth for a long period of time , adding organic carbon if cycled , preventing the system to become more autotrophic.

The production of phyriphyton is a mix of both, creating a food source with a C/N ratio of +- 10, not resulting in nitrate production. The consumption of macroalgae will provide organic carbon, leading to less nitrate production.

A bio does produce nitrate in funtion of the C/N ratio. A substrate based bio is in the first place a remineralization filter, consuming DOC, producing the elements for growth and nitrate only if not enough organic carbon is available, which normally is the case using natural feed. High protein feed will produce more nitrate. What happens with the produced ammonia if ammonia is not transformed into nitrate?

Most reefsystems use a skimmer and photo-autotrophic growth is limited by removing target nutrients, preventing balanced growth, These systems promote heterotrophic growth turning the system each cycle more and more autotrophic, producing more nitrate in time, nitrate which can not be used up by photo-autotrophic growth due to target removal of some nutrients, being a standard procedure in modern reefkeeping; This instead of preventing those targeted nutrients may accumulate. To achieve this using a skimmer is no help.


A biofilter is NOT responsible for nitrate accumulation as often published.
A skimmer my cause a system to become more autotrophic, needing more nitrate production to support the carrying capacity.

If nitrate accumulates this is not because of using a remineralisation filter, a bio, but because sufficient nitrogen consuption is not available. To much high protein feed to start with. If not enough nitrogen compsumption is avalable I prefere the nitrogen to be nitrate-nitrogen. One may start with adding less nitrogen, by lowering the protein content of the feed.

Using a system based on growth, a biofilter is used, all nitrogen will be consumed, growth is harvested. When adding a skimmer, this is not possible and AAM is made difficult, Using AAM the situation can easily be corrected using for the target nutrient modified feed, supporting growth, the opposite of what a lot of reefers do.


Ammonia is produced, if the system becomes more autotrophic I prefere this nitrogen to be stored in nitrate. Each nutrient cycle the system becomes more autotrophic as each cycle a lot of organic carbon is exported as CO2 for energy. Normally the balance is kept by photo-autotrophic growth which in most modern reeftanks is not the case.

Why nitrate may build up slowly in a well lit aquarium?

Nitrate doesn’t build up in well lit aquariums if the operator chooses to run an aggressive algae growth filter, even with foam fractionation, protein skimmer, skimmer, whatever. I maybe missing your point.

 

[nereefpat]

If the hypothesis here is:

'Protein skimmers remove certain things required for microbial and algal life but leave other required things behind, which causes an imbalance and eventual nitrate issues.'

That's a reasonable thing to test. But I think that if you do test that hypothesis, by looking at tanks with skimmers, you'll see there are lots and lots of reefers running skimmers that have very little (or nearly zero) measurable nitrate, like me for example.

I'm baffled this thread is as long as it is.

 

[Belgian Anthias]

If the hypothesis here is:

'Protein skimmers remove certain things required for microbial and algal life but leave other required things behind, which causes an imbalance and eventual nitrate issues.'

That's a reasonable thing to test. But I think that if you do test that hypothesis, by looking at tanks with skimmers, you'll see there are lots and lots of reefers running skimmers that have very little (or nearly zero) measurable nitrate, like me for example.

I'm baffled this thread is as long as it is.

iI think this was done by Feldman and Maers?

 

[Belgian Anthias]

Does a skimmer remove proteins ( the organic compound) from the tank by foam fractioning, by "air stripping"?

After consumption most nitrogen( +- 85%) present in the food ( part of protein) is released as ammonia, nitrogen to be reused for new growth, building up the protein of new cells. The nitrogen not used ,once part of proteins, may build up.
Assume the compound protein, containing the nitrogen source, comes available in the system water, it will be used immediately, leaking ammonia.

Data published by Shimek ( 2002)from a survey of 23 hobbyist aquariums report protein concentrations of 0.00+-0.00. They were not demonstrable. Which is logic.

A skimmer does not remove much proteins by foam fractioning, protein is removed being part of live cells carried on the foam produced by foam fractioning.

it has been shown ( Feldman and Maers) a skimmer does not remove a lot of stuff, what it does remove it does in a selective way.

Most stuff is reminerelized, also a lot of the skimmed stuff, where it is attached to the produced organic foam, before it ends up in the cup.

Is a skimmer able to remove proteins by foam fractioning? yes, if available

Does a skimmer export proteins? yes, being part of living cells. In any proteins are skimmed, they will be reminerelized on the foam.

To export protein ( nitrogen) we just have to harvest growth, and there are more effective and more reliable ways to do this, including the possibility for managing the export rate as desired by the user.

 

[Belgian Anthias]

More input from foods than consumption by photosynthetic organisms. Doesn't seem complicated to me.

So, why nothing is done to solve this, it is not complicated, which is true.

Why the past deccenia this has not been solved ?

Why the input is not consumed having an unlimited energy source, light,. it should not be that difficult if for growth balanced food is provided.

 

[ReefGeezer]

To export protein ( nitrogen) we just have to harvest growth, and there are more effective and more reliable ways to do this, including the possibility for managing the export rate as desired by the user.

Pardon my ignorance. I lose track of the discussion when too many scientific terms are used. Are you actually exporting proteins or are you relying on other organisms to use them and bind the N & P? What do you harvest in your system to perform export? How do you encourage the growth of whatever you are harvesting? Is excess DOC ever an issue in your tank? Do you have pictures of your tank and growth system? Thanks.