Skimmer overkill?

[NMdesertReefer]

Greetings everybody from the one and only UFO capital of the world!! So I was going to set up a 125 gallon tank but stuff happens and now I doing a 40 breeder with a 40gallon sump that it was going to be used for the 125 I had already bought a eshopps x 350 skimmer for the 125, I really don't want to buy another skimmer since I already have the x350 but it seems it's overkill for 40 breeder my total water volume would probably be around 60 gallons, what problems would I have if I run a skimmer that big what are you guys recommendations?

 

[Randy Holmes-Farley]

I'm not convinced that "overskimming" the water is a problem, or even possible.

For someone to claim it is, indicates an expected problem of some sort. What problem?

Nutrients too low? Skimming alone does not usually cause that, but if they end up too low, it is easy to feed more or dose nutrients.

Organics too low? If that is even a "problem, I don't think skimming has been shown to accomplish that nearly as readily as GAC.

too much aeration (not a problem, IMO).

So what else could it be?

Noise and expense seem the primary remaining issues. Expense is mostly already done.

So noise?

 

[AdamNC]

Other than a big footprint in your sump? Nothing. I’m running a skimmer rated at 75 gallons on a 29 gallon tank.

 

[cracker]

I like to double the rating. For example I have an old ASM on the 180 It's rated for up to 400gl . I have a reef octo rated for 200 on the 75 .total 90 gls & haven't had any probs . Try to turn it way down & see what happens. If You want more, Ya already have it.

 

[Tony Thompson]

I'm not convinced that "overskimming" the water is a problem, or even possible.

For someone to claim it is, indicates an expected problem of some sort. What problem?

Nutrients too low? Skimming alone does not usually cause that, but if they end up too low, it is easy to feed more or dose nutrients.

Organics too low? If that is even a "problem, I don't think skimming has been shown to accomplish that nearly as readily as GAC.

too much aeration (not a problem, IMO).

So what else could it be?

Noise and expense seem the primary remaining issues. Expense is mostly already done.

So noise?

IMO, whilst certainly capable of nutrient export, over skimming may have some detrimental effects to the reef tank. The skimmer by design is quite indiscriminate in what it removes. Some research ( Ken S. Feldman
Department of Chemistry, The Pennsylvania State University, University Park, PA 16802.) suggests that only approx 29% of skimmate is TOC. There is a discussion already underway on this forum, discussing some of the negative aspects of skimming. I think some may be surprised at what that "awful skimmate" contains.

 

[Randy Holmes-Farley]

IMO, whilst certainly capable of nutrient export, over skimming may have some detrimental effects to the reef tank. The skimmer by design is quite indiscriminate in what it removes. Some research ( Ken S. Feldman
Department of Chemistry, The Pennsylvania State University, University Park, PA 16802.) suggests that only approx 29% of skimmate is TOC. There is a discussion already underway on this forum, discussing some of the negative aspects of skimming. I think some may be surprised at what that "awful skimmate" contains.

I'm pretty aware of what skimmate contains, as well as Ken's articles. Do you have something in mind that is a problem if exported?

I've not seen anything to be particularly concerned about, and as I recall, Ken's articles did not really support the idea that big skimmers removed all that much more TOC than smaller ones:

https://www.advancedaquarist.com/2010/1/aafeature

"The results to date on protein skimming as a means of aquarium water remediation form a consistent picture that is at odds with some of the cherished dogma in the marine husbandry area. According to the data presented in this and the earlier paper (Advanced Aquarist, January 2009), protein skimmers appear to have a much larger variation in their prices than they do in their ability to remove TOC from aquarium water. Recent design innovations like bubble plates, conical sides, or pinwheel impellers do not seem to impact significantly on either rate of TOC removal or amount of TOC removed, at least for the skimmers tested. Thus, skimmer manufacturer claims about enhanced organic removal capabilities should be met with skepticism in the absence of compelling and quantitative TOC removal data."

 

[shred5]

While I do not think you can over skim you can have to large of a skimmer where if there are not enough organics to create a stable foam and it will just sit in the neck and never overflow into the cup. You end up with a coating in the neck and not much in the cup. Skimmer should not only be based on the size of the tank but also the load on a tank. I have seen reefs with more load on a 75 than a 120. Tank size does matter on the amount of water processed, meaning you do not want such a small skimmer on a large tank most of the water bypasses a skimmer.

I do not have time to look up your skimmer to see if it is to big I have to leave for work.

 

[Tony Thompson]

I'm pretty aware of what skimmate contains, as well as Ken's articles. Do you have something in mind that is a problem if exported?

I've not seen anything to be particularly concerned about, and as I recall, Ken's articles did not really support the idea that big skimmers removed all that much more TOC than smaller ones:

https://www.advancedaquarist.com/2010/1/aafeature

"The results to date on protein skimming as a means of aquarium water remediation form a consistent picture that is at odds with some of the cherished dogma in the marine husbandry area. According to the data presented in this and the earlier paper (Advanced Aquarist, January 2009), protein skimmers appear to have a much larger variation in their prices than they do in their ability to remove TOC from aquarium water. Recent design innovations like bubble plates, conical sides, or pinwheel impellers do not seem to impact significantly on either rate of TOC removal or amount of TOC removed, at least for the skimmers tested. Thus, skimmer manufacturer claims about enhanced organic removal capabilities should be met with skepticism in the absence of compelling and quantitative TOC removal data."

Hi Randy, as a respected and qualified member of both academia and the reefing community I think your input on the discussion I mentioned would be highly appreciated. I am very aware that you will have detailed knowledge about the chemical and biological make up of skimmate as well as any current research. that`s why my sentence read "some may be surprised" I apologize if you took this as reference to yourself.

As a hobbyist, my own personal interest is trying to put some science behind what I observe in my Reef Tanks. I am neither qualified or experienced enough to make any definite conclusions. However I along with a number of fellow reefers, have noticed that by reducing the period of skimming, created an appearance of improvements in both colouration and polyp extension, especially in the group of corals labelled LPS.

I understand your reference to skimmer size and percentage of TOC removed. My focus is not on the amount of TOC in general but the other contents of the skimmate. specifically those elements (biological and chemical) that are generally regarded as useful to the reef aquarium.

Once again I apologise for posting yet another reference to an article that I am sure you are already aware of, but the following article is directly linked to my previous conclusion.
Bacterial Counts in Reef Aquarium Water: Baseline Values and Modulation by Carbon Dosing, Protein Skimming, and Granular Activated Carbon Filtration
By Ken S. Feldman, Allison A. Place, Sanjay Joshi, Gary White)

Could you please explain in a little more detail your statement that larger skimmers do not remove more TOC than small ones. Surely the amount of TOC is in respect to the percentage of the total removed. not the amount as volume removed. I don`t` understand how a small skimmer can remove the same amount of TOC by volume over a set period than a much larger one would on the same tank.

I Really appreciate the chance to have access to people of your qualification. As a hobbyist I have so many questions to my observations, I will try and stay on point. Thanks.

 

[PatW]

Skimmers are usually over rated on tank volume. If you go to Bulk Reef Supply, they rate skimmers for low, medium and high stocking levels. My own skimmer is rated at 500 gallons on a 300 gallon tank. And Mr. Saltwater Tank recommends getting a skimmer that is plus 1 meaning at least a step bigger than your system.

 

[NMdesertReefer]

Thank you everybody for your input, it seems that almost every body agrees that you can't overskimm, I'll use the skimmer I have and if I see that I don't have enough organics to make it up the cone maybe I can put the skimmer on a schedule or will it be a problem to have the skimmer turn on and off and having to be readjusted after it's been off?

 

[Randy Holmes-Farley]

Hi Randy, as a respected and qualified member of both academia and the reefing community I think your input on the discussion I mentioned would be highly appreciated. I am very aware that you will have detailed knowledge about the chemical and biological make up of skimmate as well as any current research. that`s why my sentence read "some may be surprised" I apologize if you took this as reference to yourself.

As a hobbyist, my own personal interest is trying to put some science behind what I observe in my Reef Tanks. I am neither qualified or experienced enough to make any definite conclusions. However I along with a number of fellow reefers, have noticed that by reducing the period of skimming, created an appearance of improvements in both colouration and polyp extension, especially in the group of corals labelled LPS.

I understand your reference to skimmer size and percentage of TOC removed. My focus is not on the amount of TOC in general but the other contents of the skimmate. specifically those elements (biological and chemical) that are generally regarded as useful to the reef aquarium.

Once again I apologise for posting yet another reference to an article that I am sure you are already aware of, but the following article is directly linked to my previous conclusion.
Bacterial Counts in Reef Aquarium Water: Baseline Values and Modulation by Carbon Dosing, Protein Skimming, and Granular Activated Carbon Filtration
By Ken S. Feldman, Allison A. Place, Sanjay Joshi, Gary White)

Could you please explain in a little more detail your statement that larger skimmers do not remove more TOC than small ones. Surely the amount of TOC is in respect to the percentage of the total removed. not the amount as volume removed. I don`t` understand how a small skimmer can remove the same amount of TOC by volume over a set period than a much larger one would on the same tank.

I Really appreciate the chance to have access to people of your qualification. As a hobbyist I have so many questions to my observations, I will try and stay on point. Thanks.

Thanks for the kind words.

Let me just clarify my thoughts on overskimming if we want to go into details. There are lots of things skimmers do, and people obviously have great tanks with no skimming, so I think arguments about skimming could range from none to huge amounts, what is best? There certainly are some situations where some aspects of skimming might be a negative, even if other aspects in the same tank are a positive, and only the aquarist can decide what is a net benefit.

Among the many things skimmers do is aerate (especially important for CO2 and O2). I would run a skimmer for that purpose alone, and in my tank, when I experimented with no skimming, the pH went too high (I used limewater) and I did not prefer the pH range that resulted. In my situation, too much aeration is not a real probability.

But in some tanks in a high CO2 home environment, it might actually be best to not aerate during the peak hours of the day, and to let photosynthesis carry the pH upwards from the low level that might be attained if the water was in perfect equilibrium with the air. Studies have shown that even a short pH peak can help corals relative to spending all their time at low pH. So in this case, no skimming or less skimming during the day could be a net plus.

Another thing that skimmers do is remove organics. Some may be toxins that have no real positive benefit, so good riddence. Others may be materials that corals, or other organisms could consume. They may also be food for bacteria that in turn can become food for other organisms. Organics have a myriad of effects, from "bad" to "good". Is removing organics overall a benefit? Is too much removal bad? This topic alone could be discussed endlessly. I believe that removing organics overall and then adding back specific ones that you think are beneficial (if any are needed; these might be amino acids, vinegar, vodka, fatty acids, foods in general, etc.; lots of possibilities) may be a better plan than just accepting what organics are naturally present, but again, that's debatable and others may choose different methods. So skimming and more skimming might be debated as to the benefit in this regard.

Another thing that skimmers do is remove N, P, and a mix of trace elements (such a copper and iron) that are part of, or bound to, organics that get skimmed out. Whether that export is desirable or undesirable, and whether it can be overdone depends entirely on the tank and whether it has too much, just enough, or too little of each and every one of those components. A heavily skimmed tank might need more of certain trace elements or inorganic nutrients (or foods) to maintain enough of them when a lighter skimmed tank might need less. Having a constant export of these things (by skimming, macroalgae, etc.) that you then add back just what you want or need is the essence of high testing methods like Triton, but I recognize they are a lot of work and expense and may not be everyone's cup of tea. If you are not monitoring closely, it might be possible to under or over skim, depending on what you consider to be the most important thing to gauge whether you are doing one or the other. If you monitor sufficiently, overskimming may not be a concern.

You mentioned bacteria, and certainly skimmers can remove some bacteria. Is that beneficial? Not sure. It may depend on the tank. Can you remove too much? Again, I'm not sure. In both cases the answer may depend on what criteria is being used to determine whether the bacteria and their export are a benefit or a detriment. I do think it is relatively easy to boost bacteria by organic carbon dosing, if not by other means. Despite having a decent (not super) skimmer, I could easily dose enough vinegar to make the water cloudy with microoorganisms. That might be a benefit for feeding filter feeders, and might be a good nutrient control mechanism. Skimming them out may have benefits (N and P export from the tank system) or detriments (reduced feeding potential, too low of N and P, etc.).

All of these things a skimmer might do represent a balance. I think that regardless of the extent of skimming (within reason), I could attain a good balance of all of these in a reef tank with appropriate foods, dosing, etc. Does that mean it is the best way to attain that balance? Not sure. I'm not even sure that all reefers identify "best" the same way (time, cost, results only, etc.) Might attaining this balance be easier with lesser skimming? Maybe with no skimming? Maybe. Maybe.

I think there are loads of possibilities for reef tank husbandry, and the question of overskimming being bad may not have a single "true" answer.

Is it possible to overskim? Well, certainly yes in some scenarios. Too much skimming could be undesirable in some situations or times of the day.

Can the same positive results be attained in a tank with a lot of skimming and appropriate "other" measures, compared to lesser skimming in that tank and different "other" measures? Probably yes.

Which is "best"? I'm not sure. I'm not even sure there is a single answer that folks would agree on after seeing the results.

 

[Tony Thompson]

Thanks for the kind words.

Let me just clarify my thoughts on overskimming if we want to go into details. There are lots of things skimmers do, and people obviously have great tanks with no skimming, so I think arguments about skimming could range from none to huge amounts, what is best? There certainly are some situations where some aspects of skimming might be a negative, even if other aspects in the same tank are a positive, and only the aquarist can decide what is a net benefit.

Among the many things skimmers do is aerate (especially important for CO2 and O2). I would run a skimmer for that purpose alone, and in my tank, when I experimented with no skimming, the pH went too high (I used limewater) and I did not prefer the pH range that resulted. In my situation, too much aeration is not a real probability.

But in some tanks in a high CO2 home environment, it might actually be best to not aerate during the peak hours of the day, and to let photosynthesis carry the pH upwards from the low level that might be attained if the water was in perfect equilibrium with the air. Studies have shown that even a short pH peak can help corals relative to spending all their time at low pH. So in this case, no skimming or less skimming during the day could be a net plus.

Another thing that skimmers do is remove organics. Some may be toxins that have no real positive benefit, so good riddence. Others may be materials that corals, or other organisms could consume. They may also be food for bacteria that in turn can become food for other organisms. Organics have a myriad of effects, from "bad" to "good". Is removing organics overall a benefit? Is too much removal bad? This topic alone could be discussed endlessly. I believe that removing organics overall and then adding back specific ones that you think are beneficial (if any are needed; these might be amino acids, vinegar, vodka, fatty acids, foods in general, etc.; lots of possibilities) may be a better plan than just accepting what organics are naturally present, but again, that's debatable and others may choose different methods. So skimming and more skimming might be debated as to the benefit in this regard.

Another thing that skimmers do is remove N, P, and a mix of trace elements (such a copper and iron) that are part of, or bound to, organics that get skimmed out. Whether that export is desirable or undesirable, and whether it can be overdone depends entirely on the tank and whether it has too much, just enough, or too little of each and every one of those components. A heavily skimmed tank might need more of certain trace elements or inorganic nutrients (or foods) to maintain enough of them when a lighter skimmed tank might need less. Having a constant export of these things (by skimming, macroalgae, etc.) that you then add back just what you want or need is the essence of high testing methods like Triton, but I recognize they are a lot of work and expense and may not be everyone's cup of tea. If you are not monitoring closely, it might be possible to under or over skim, depending on what you consider to be the most important thing to gauge whether you are doing one or the other. If you monitor sufficiently, overskimming may not be a concern.

You mentioned bacteria, and certainly skimmers can remove some bacteria. Is that beneficial? Not sure. It may depend on the tank. Can you remove too much? Again, I'm not sure. In both cases the answer may depend on what criteria is being used to determine whether the bacteria and their export are a benefit or a detriment. I do think it is relatively easy to boost bacteria by organic carbon dosing, if not by other means. Despite having a decent (not super) skimmer, I could easily dose enough vinegar to make the water cloudy with microoorganisms. That might be a benefit for feeding filter feeders, and might be a good nutrient control mechanism. Skimming them out may have benefits (N and P export from the tank system) or detriments (reduced feeding potential, too low of N and P, etc.).

All of these things a skimmer might do represent a balance. I think that regardless of the extent of skimming (within reason), I could attain a good balance of all of these in a reef tank with appropriate foods, dosing, etc. Does that mean it is the best way to attain that balance? Not sure. I'm not even sure that all reefers identify "best" the same way (time, cost, results only, etc.) Might attaining this balance be easier with lesser skimming? Maybe with no skimming? Maybe. Maybe.

I think there are loads of possibilities for reef tank husbandry, and the question of overskimming being bad may not have a single "true" answer.

Is it possible to overskim? Well, certainly yes in some scenarios. Too much skimming could be undesirable in some situations or times of the day.

Can the same positive results be attained in a tank with a lot of skimming and appropriate "other" measures, compared to lesser skimming in that tank and different "other" measures? Probably yes.

Which is "best"? I'm not sure. I'm not even sure there is a single answer that folks would agree on after seeing the results.

Hi again Randy, thank you for the excellent write up. This is one of the reasons I love forums such as R2R. Carefully thought out, Bi partisan opinion, backed up with qualified experience and peer reviewed data. I really appreciate the time you have taken to make these points so clear.

I must admit I am a very skeptical reefer, enough to make even Richard Ross seem conformist, ha ha.

I like many, do not have an endless budget for my hobby, therefore I have to choose very carefully whether a manufacturers claims are in fact worth the investment. I believe you touched on this aspect with regards skimmer design. I hear time and time again reefers excaliaming the virtues of their latest skimmer purchase, calculated by the amount of skimmate it produces.

My conclusion is. Can a skimmer be a useful tool in the reef aquarium? Yes.

Does this mean a bigger and more productive skimmer increase its usefulness? I believe that question can only be answered once you are aware of the full implications of skimming and wether this meets your needs.

Can you over skim? IMO, a rather tenuous, Yes. But only if If you feel that some of the elements removed by skimming are important to your particular method of reefing. With the proviso that you have a preference to what, if any, of the depletion levels are acceptable

Thanks Randy and best wishes from over the pond.

Sorry, NMDesertReefer if I have inadvertently hijacked your thread. Hope you are happy with your choice and best wishes with your 40G tank, even that is a big tank for me I am a Nano / Pico enthusiast.

 

[NMdesertReefer]

Hi again Randy, thank you for the excellent write up. This is one of the reasons I love forums such as R2R. Carefully thought out, Bi partisan opinion, backed up with qualified experience and peer reviewed data. I really appreciate the time you have taken to make these points so clear.

I must admit I am a very skeptical reefer, enough to make even Richard Ross seem conformist, ha ha.

I like many, do not have an endless budget for my hobby, therefore I have to choose very carefully whether a manufacturers claims are in fact worth the investment. I believe you touched on this aspect with regards skimmer design. I hear time and time again reefers excaliaming the virtues of their latest skimmer purchase, calculated by the amount of skimmate it produces.

My conclusion is. Can a skimmer be a useful tool in the reef aquarium? Yes.

Does this mean a bigger and more productive skimmer increase its usefulness? I believe that question can only be answered once you are aware of the full implications of skimming and wether this meets your needs.

Can you over skim? IMO, a rather tenuous, Yes. But only if If you feel that some of the elements removed by skimming are important to your particular method of reefing. With the proviso that you have a preference to what, if any, of the depletion levels are acceptable

Thanks Randy and best wishes from over the pond.

Sorry, NMDesertReefer if I have inadvertently hijacked your thread. Hope you are happy with your choice and best wishes with your 40G tank, even that is a big tank for me I am a Nano / Pico enthusiast.

Don't have to be sorry for anything, I love this I've learned more than I was expecting by asking what seemed to me a small and simple question.

 

[Tony Thompson]

While I do not think you can over skim you can have to large of a skimmer where if there are not enough organics to create a stable foam and it will just sit in the neck and never overflow into the cup. You end up with a coating in the neck and not much in the cup. Skimmer should not only be based on the size of the tank but also the load on a tank. I have seen reefs with more load on a 75 than a 120. Tank size does matter on the amount of water processed, meaning you do not want such a small skimmer on a large tank most of the water bypasses a skimmer.

I do not have time to look up your skimmer to see if it is to big I have to leave for work.

Really good point, shred5. I hear this quite often, where people complain about their particular brand of skimmer because it does not produce enough skimmate. So decide to buy a more expensive, larger skimmer. As you mentioned, this could possibly be a lack substantial organics to support the bubble column. Its probably a smaller skimmer with smaller reaction chamber they need if anything. Even worse some people lower the skimmer in the water column or adjusting the vent and skim wet. This in my opinion could possibly increase the negative effects of skimming. Emptying your skimmer cup of water every day and replacing it with RODI, does not seem like a good idea to me.

 

[shred5]

Really good point, shred5. I hear this quite often, where people complain about their particular brand of skimmer because it does not produce enough skimmate. So decide to buy a more expensive, larger skimmer. As you mentioned, this could possibly be a lack substantial organics to support the bubble column. Its probably a smaller skimmer with smaller reaction chamber they need if anything. Even worse some people lower the skimmer in the water column or adjusting the vent and skim wet. This in my opinion could possibly increase the negative effects of skimming. Emptying your skimmer cup of water every day and replacing it with RODI, does not seem like a good idea to me.

Usually a skimmer does not perform well because it is poorly designed. Allot of companies just build a skimmer and pick a pump in the range instead of building the skimmer for the pump. That is why one skimmer in a line can perform well and another wont. Happens allot with lower priced skimmers. Three things usually cause poor skimming.

A pump that pulls to much water for the skimmer body size and causes allot of turbulence.

A neck two large for the amount of air and then the foam rarely has enough air to overflow into the cup, this is rare.

A neck that is too small for the amount of air being fed into it and it overflows and is not stable. This is the most common but is usually a easy to fix by putting a air valve on the venturi tube.. Anyone that has a touchy overflowing skimmer just put a air valve on and give that a try, it may make your skimmer a awsume skimmer.

 

[Randy Holmes-Farley]

Thanks Randy and best wishes from over the pond.

Thank you, and happy reefing.

 

[siggy]

Hi again Randy, thank you for the excellent write up. This is one of the reasons I love forums such as R2R. Carefully thought out, Bi partisan opinion, backed up with qualified experience and peer reviewed data. I really appreciate the time you have taken to make these points so clear.

+1

a smaller skimmer with smaller reaction chamber they need if anything.

I recently switched out my skimmer on my 75G to a RO150 from a mini monster, The mini produced a ton. I have added several fish and N&P increased due to feeding thus the upgraded skimmer. The new skimmer is huge and I see that all the points made by several of you about the neck being to big and foam not reaching the top has me rethinking my decision. I'll wait for the break in period and may just skim at night.