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Old 11/09/2017, 12:29 PM   #1
mathman7728
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does heavy skimming remove PO4 and/or NO3?

as the title says, will skimming cause a drop in P04 and/or NO3. for example, i have high NO3 but .04-.06 PO4 (which is think is a good level for mixed reef) and wondered if skimming more reduce NO but no PO?

thank you!


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Old 11/09/2017, 12:50 PM   #2
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does heavy skimming remove PO4 and/or NO3?

i think the answer is no but i'll wait and see what others say



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Old 11/09/2017, 12:59 PM   #3
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The short answer is no.

The long answer is noooooo.

They remove dissolved organics, like fish poop.

http://reefkeeping.com/issues/2002-0...ture/index.htm


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Old 11/09/2017, 01:11 PM   #4
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Skimming does not remove PO4 or NO3 directly; but, does remove organics which might otherwise decay in the tank adding inorganic N and P as a result.


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Old 11/09/2017, 02:59 PM   #5
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Originally Posted by tmz View Post
Skimming does not remove PO4 or NO3 directly; but, does remove organics which might otherwise decay in the tank adding inorganic N and P as a result.
^^That..
Skimming will never reduce your current nitrate or phosphate levels.. But it can keep them from going higher...


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Old 11/09/2017, 04:08 PM   #6
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Dissolved nutrients generally can't be removed by skimming. Phosphate can be removed only at an interesting rate if it's still attached to an organic. Of course, any skimmer will remove a bit of the water column, which amounts to an incredibly tiny water change.


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Old 11/09/2017, 08:54 PM   #7
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I do believe the skimmer will remove phosphate and nitrate but not directly. People that carbon dose do indeed see increased skimmate production and it's thought that the bacteria which are feeding off the phosphate and nitrate are a part of the skimmate that you collect.


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Old 11/09/2017, 09:58 PM   #8
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The bacteria are organic and consume dissolved Nand P and do seem to be caught in the air/water space between the skimmer bubbles and most amphipathic organics are.


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Old 11/10/2017, 04:01 AM   #9
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I can detect phosphate, ammonia and nitrate in the skimmate. The nitrate level in the skimmate seems to be correlated to the amount in the aquarium water. I assume this means it is not concentrated but carried over. Recently, I measured ammonia between 0.5-8 ppm in foamate. Concentrating ammonia might happen through the skimming of a large organic acid salt of ammonia, though I have not investigated why an ammonium salt would exist in a sea of sodium ions. Another explanation is that the salicylate test is detecting an organic amine. Skimming also captures microalgae (skimmate fluoresces under long wavelngth UV) and bacteria. Maybe test conditions break open the cells, releasing ammonia. Since fresh skimmate also shows ammonia, it is probably not due to bacteria metabolism after the skimmate is collected though I am still not a 100% convinced. Phosphate is detected in the 0.2-2 ppm range and might be concentrated with a large basic organic molecule or comes over in the shells of phytoplankton. Support for the latter notion is that acidifying the solid in the skimmate with dilute HCl for five minutes generated twice the amount of dissolved phosphate than in the liquid. Also, the phosphate test conditions might be acidic enough to dissolve some of this solid, giving the illusion of dissolved phosphate. Overall, a skimmer removes nitrogen and phosphorous in amounts that are useful but not substantial. Given the volume of skimmate my skimmer collects per day, phosphate is reduced in the aquarium by 0.001 ppm per day.


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Old 11/10/2017, 10:36 AM   #10
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The water a protein skimmer pushes to the cup will pass along some small amounts of dissolved nutrients like a very small water change will as Jon noted.

The rising flow action in the skimmer will also push along bits of this and that algae detritus bacteria etc.

However, the foam fractionation function( the actual "skimming") relies on the attraction of organic molecules to water and their repulsion from it. Amphipathic molecules like proteins and others with bi-polarity are pulled toward the water on one side and repelled by it on the other. These ampipathic molecules are most susceptible to removal via skimming as they get cling to the air and water surface there at the same time and get trapped between the bubbles.


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Old 11/10/2017, 03:29 PM   #11
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Quote:
Originally Posted by hkgar View Post
The short answer is no.

The long answer is noooooo.



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Old 11/10/2017, 04:37 PM   #12
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Oops, I should have posted this article:

http://reefkeeping.com/issues/2006-08/rhf/index.php


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Old 11/10/2017, 05:05 PM   #13
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Originally Posted by tmz View Post
The water a protein skimmer pushes to the cup will pass along some small amounts of dissolved nutrients like a very small water change will as Jon noted.

The rising flow action in the skimmer will also push along bits of this and that algae detritus bacteria etc.
Very small particles like bacteria and phytoplankton are not pushed along but rather experience similar forces as molecules that adhere to the water air interface. Shine a black light on skimmate and you are likely to see it fluoresce due to all the phytoplankton chlorophyll. This amount of phytoplankton would not accumulate by entrainment of debris in the aquarium water. In addition, some of the solids or slime seen in the skimmate are likely material that has agglomerated or precipitated as a result being concentrated in the foam.


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Old 11/10/2017, 07:41 PM   #14
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Skimming does not remove PO4 or NO3 directly; but, does remove organics which might otherwise decay in the tank adding inorganic N and P as a result.
By organics, would that include free swimming bacteria?

PS. I jumped in to soon as I see that the answer for bacteria was already covered.


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Old 11/10/2017, 07:52 PM   #15
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Originally Posted by mathman7728 View Post
as the title says, will skimming cause a drop in P04 and/or NO3. for example, i have high NO3 but .04-.06 PO4 (which is think is a good level for mixed reef) and wondered if skimming more reduce NO but no PO?

thank you!
Of course skimming reduces both nitrate and phosphate. While difficult to analyze it is mostly composed of bacteria which should line up with the Redfield Ratio.

Why do you ask about the ratio of nitrate to phosphate?

What do you call high nitrate?


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Old 11/11/2017, 09:39 AM   #16
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Very small particles like bacteria and phytoplankton are not pushed along but rather experience similar forces as molecules that adhere to the water air interface.


Why do you exclude upward flow as a force moving organics and small particulate matter upward. Upwelling is a part of how reefs work. Amphipathic and hydrophobic planktonic microrganisms and particulate matter are attracted to the air water interfaces but that does not exclude the effect of upward flow on them.


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Old 11/11/2017, 06:47 PM   #17
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Very small particles like bacteria and phytoplankton are not pushed along but rather experience similar forces as molecules that adhere to the water air interface.


Why do you exclude upward flow as a force moving organics and small particulate matter upward. Upwelling is a part of how reefs work. Amphipathic and hydrophobic planktonic microrganisms and particulate matter are attracted to the air water interfaces but that does not exclude the effect of upward flow on them.
The upwelling of water in the ocean moves bulk water and it's contents to other regions. If the other region is lower in organic content, the concentration increases when the richer water is mixed in. It does not act at the molecular level to preferentially "move" molecules or at the micron level to move sub micron particles.

In the case of a skimmer, the upwelling is not water but air in the form of tiny bubbles. Aquarium water mixes with the bubbles and rises with the air into the skimmer throat. It is still just aquarium water mixed with air. Nothing additional has been swept along because there is nothing additional brought along but the material in the aquarium water. So very wet skimming is barely different from a water water change. The upward movement of water in the skimmer, the water entrained in the foam, is doing nothing to change the material concentration as it moves higher up in the skimmer column or skimmer thoat. The concentration of material we observe in skimmate is a result of the bubble breakage and the concentrated material reentering the water in the foam and re-attaching to bubbles, strengthening them which results in them lasting longer and eventually leaving the skimmer throat top. In addition, the water entrained in the foam drains away in the skimmer throat, also giving a dryer, more concentrated foam. Upward flow by itself is not part of the foam fractionation mechanism of concentration of molecules and particulates.


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Old 11/13/2017, 01:43 PM   #18
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The upwelling is water moving with the bubbles . Most skimmers create a significant upward flow . Reef's move water upward via advective flow.
The differentiation between upward flow and foam fractionation was clear in my earlier post. Nonetheless ,a"bit" of unbound material will move in an upward flow and some of that ,probably a small amount will settle in the skimmate, in my view.


This from Randy's article previously cited explains it better:




[B]"...The froth of bubbles begins to drain under gravity, removing much of the water between the bubbles. Some of the bubbles merge into larger bubbles. As long as the bubbles do not pop before significant draining occurs, then the organics will be left behind in the foam, along with some residual water. Eventually, the concentration of organics on the top of the foam becomes great enough that they exceed the solubility limit, and small particulates of organics form. These particulates are generally what a skimmer collects, along with some water and organics that remain present in solution or at the air/water interface...."[B]

So, I don't think all of the material in the skimmate results from molecular attachment at the air water interface ; some albiet arguably a very small amount can be pushed along with the water .


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Old 11/14/2017, 12:51 AM   #19
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After adding nori or ground shellfish to my tank, I definitely see it start to rise out of the collection cup on my recirc skimmer. I’d argue that the upflow of bubbles as well as solubilty characteristics of the bubble interface both aid in this effect. Watching the top of the skimmer bubbles closely, in certain cases I have seen the organics dancing across the bubble surface and precipitate! Surely a better name for protein skimmers would be surfactant skimmer

Carbon dosing definetly sequesters no3 and po4 into skimmable microorganisms. Skimming cannot remove appreciable amounts of inorganic nutrients like no3 or po4, but is excellent at removing organic nutrients as they contain surfactant like qualities. Microorganisms are covered in negative surfactants. If the quantity of surfactants drops below a critical concentration, the foam level falls.

Measuring nitrate or phosphate in skimmate is likely useless. Microorganisms are both growing and dying/lysing in the skimmate shuffling nutrients between organic and inorganic states.


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Old 11/14/2017, 10:59 AM   #20
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That's how I view it : nicely stated. I've also seen "bits of this and that " in skimmate cup and the skimmer water column.

Decaying organics there will release nutrients and other elements; some consumption might also occur;measurements likely chart a false trail


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Old 11/14/2017, 05:08 PM   #21
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After adding nori or ground shellfish to my tank, I definitely see it start to rise out of the collection cup on my recirc skimmer. I’d argue that the upflow of bubbles as well as solubilty characteristics of the bubble interface both aid in this effect.
You could argue that the upflow of bubbles was a contributing factor but you will find no scientific research to back up your arguement. The operation of foam fractionation and froth flotation are understood and “up flow” per se has nothing to do with the mechanism by which these devices separate hydrophobic material from water. If you ran a foam fractionator in outer space, i.e., zero G, where there is no up flow, it would work just as well, though I doubt anyone has.


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Old 11/15/2017, 10:11 AM   #22
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Ehtereal agumments and black holes aside, simply stated flowing water moves material on earth;skimmer's create significant upward flow; whether or not the movement of a particular particle is aided by foam fractionation depends on the amphipathic qaulity of the particle.


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Old 11/15/2017, 04:50 PM   #23
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Ehtereal agumments and black holes aside, simply stated flowing water moves material on earth;skimmer's create significant upward flow; whether or not the movement of a particular particle is aided by foam fractionation depends on the amphipathic qaulity of the particle.
Sure, what you state is true, flowing water moves things, and skimmer flow moves upwards, but all this is not really relevant in discussing how skimmers operate, that is, how they concentrate material and how things end up in the collection cup. If by chance a particle is caught in the flow, it could end up in the collection cup. And if this chance occurrence is what you are talking about, then OK!


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Old 11/15/2017, 11:44 PM   #24
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If there is no gravity, bubbles would not rise. I would guess a skimmer in outer space would not work. Heck holding water in a cup in outer space wouldn't work.

On a scientific note, if I put my face above my skimmer collection cup, I can feel air flowing out at a very appreciable rate.

Quote:
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You could argue that the upflow of bubbles was a contributing factor but you will find no scientific research to back up your arguement. The operation of foam fractionation and froth flotation are understood and “up flow” per se has nothing to do with the mechanism by which these devices separate hydrophobic material from water. If you ran a foam fractionator in outer space, i.e., zero G, where there is no up flow, it would work just as well, though I doubt anyone has.



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Old 11/16/2017, 10:30 AM   #25
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Sure, what you state is true, flowing water moves things, and skimmer flow moves upwards, but all this is not really relevant in discussing how skimmers operate, that is, how they concentrate material and how things end up in the collection cup. If by chance a particle is caught in the flow, it could end up in the collection cup. And if this chance occurrence is what you are talking about, then OK!
That's what I said in post #10. Upward flow is part of what skimmers do;so is aeration btw:


The water a protein skimmer pushes to the cup will pass along some small amounts of dissolved nutrients like a very small water change will as Jon noted.

The rising flow action in the skimmer will also push along bits of this and that algae detritus bacteria etc.

However, the foam fractionation function( the actual "skimming") relies on the attraction of organic molecules to water and their repulsion from it. Amphipathic molecules like proteins and others with bi-polarity are pulled toward the water on one side and repelled by it on the other. These ampipathic molecules are most susceptible to removal via skimming as they get cling to the air and water surface there at the same time and get trapped between the bubbles.


I have no idea why you chose to contradict it in absolute terms.



The movement of particulate matter via flow is relevant to the OPs question about nutrient removal and a part ,albeit perhaps a small one, of the way skimmers operate. Some of the bits of material moved along by the flow to the cup would otherwise decay or dissolve in the tank and do also account for some of the content of the skimmate.


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