Is it possible to overskim a reeftank?

[jmaneyapanda]

I dont think I'm making my point clear. What difference does it make if the DOS is in the neck or the cup? The point is it is not in the tank. And the biochemistry of foam fractionation wont allow it back to the water column (unless the skimmer pump is turned off, or air inlet blocked, or other anomolous action). The whole concept of wet and dry skimmate is quite misunderstood. The only difference between the two is the amount of saltwater you push out with the waste. Why do you think you'll need to wet skim to push out the DOS? It can eternally just accumulate in the neck, until the volume is enough to pour into the skimmate cup. Using my method just described, or your wet skim method will yield the exact same waste removal.

I disgaree with the break in period comment, also. Why do you think this?

Now, I agree that the setup cost is greater, the operating cost is greater, and their may be some issues if your sump hold 20 gallons, and your skimmer feed pump calls for 1800 gallons per hour, but this is all oblivious to the effeciency of the skimmer. And setup of the larger one is certainly no more difficult whether it is on a large or small tank. The larger skimmer will very likely keep the water cleaner, than any comperable smaller one, with no more adjustment than the smaller one.

 

[cameron]

jmaneyapanda wrote: I dont think I'm making my point clear.

You are... I am just dense.

jmaneyapanda wrote: What difference does it make if the DOS is in the neck or the cup?

Foam doesn't stay foam for long. It dries up and gets crusty. If your aren't removing the DOS from the skimmer frequently enough, it begins to smell quite bad. I took a wiff recently of some that was almost a month old... it isn't pleasant. So at some point if your DOS isn't going in the cup in a timely manner you are probably going to throttle the skimmer to push it into the cup. You are correct that the crap is out of the water (as I have agreed to several times earlier), but it is still a smelly mess.

jmaneyapanda wrote: I disgaree with the break in period comment, also. Why do you think this?

A larger skimmer has a larger surface area which means more "slime" has to build up. It takes more nutrients to build that up and a higher flow rate into the skimmer. If you aren't throwing the optimum flow through the skimmer or your bioload is less than recommended, the break in time takes longer. I think there is some vinegar trick to get it skimming out of the gate, but not sure what that is.

jmaneyapanda wrote: And setup of the larger one is certainly no more difficult whether it is on a large or small tank.

This gets into specific setups, but if you aren't pulling the proper volume of water through your skimmer you aren't using it effectively and the user will have to dial it in more than a skimmer that is getting the proper flow. Most of the higher end systems use gate valves which make this easy negating this point, but I did mention that in my original post. If you are sending the full recommend gph from a small system into a huge skimmer, then you are right. However, you will be turning over a lot water in the sump or your fish will be doing a lot of current swimming .

jmaneyapanda wrote: The larger skimmer will very likely keep the water cleaner, than any comperable smaller one, with no more adjustment than the smaller one.

A good skimmer that is appropriately sized will pull about the same amount of DOS from a tank as a larger one. Size does not equal effeciency and you can only pull so much out of a tank based on bio-load. Larger does not equal better which is the round-about point I have been trying to make.

Again this is just mostly theory and little practice.

 

[jmaneyapanda]

I think we'll have to agree to disagree. I don't see the DOS magically turning good once it hits the collection cup. It is the same thing as it is in the neck. So, whether you clean it from the cup or the neck, it is still out. I still don't think you will need to wet skim it out. Eventually, as skimmate accumulates in the neck, it will raise and go into the collection cups, and not really dry out.

Yes, larger skimmers have larger surface areas to acclimate. But, the supply pump is usually proportionally larger also. So, it gets more water, and should acclimate in no less time. All of my argument assumes that there is appropriately sized pumps and equipment to the skimmer. If you're discussing a large skimmer with a undersized pump, I am not commenting on this. But, if the bioload is smaller than you skimmer is rated, it will still pull out the organics at a higher rate than a smaller skimmer. Because more water goes through quicker, and gets more air to water contact. You are assuming the "appropriately" sized skimmer is pulling out 100% of the organics. That is not an assumption I am willing to make. If any given skimmer only pulls out a percentage of the available organics, then, the greater the frequency (flow through and contact time), the better the effeciency.

You mentioned that larger skimmers have to be "dialed in" for the proper flow. But medium sized ones do not? All skimmers should have appropriate water flow into and out of the reaction chamber, no matter what the size. To say this is more difficult in large skimmer is imprecise. It is no different than on a medium or small siozed skimmer.

As you said, I think there are other considerations when running a very large skimmer on a small tank, but I strongly believe that effeciency and operation and setup are not compromised or made more difficult in this case.

 

[cameron]

jmaneyapanda wrote: I don't see the DOS magically turning good once it hits the collection cup. It is the same thing as it is in the neck. So, whether you clean it from the cup or the neck, it is still out.

Anything in the neck that isn't stuck to the sides will flush back into the skimmer when you shut it off. Best to throttle it and kick it in the cup so you can dispose of it properly.

jmaneyapanda wrote: Yes, larger skimmers have larger surface areas to acclimate. But, the supply pump is usually proportionally larger also.

Bioload has a lot to do with priming the skimmer. If you run the oversize skimmer at the recommended flow, either it is going to keep reskimming the water in the sump which does you no good or you are going to create a HUGE amount of flow through the entire system which really isn't very practical. Assuming you do cycle the entire system through the skimmer say 10 times every hour it still isn't going to pull anymore DOS out of the system than a properly sized skimmer. A good properly sized skimmer is going to coat faster because it is pulling roughly the same amount of DOS out sliming a smaller surface.

You are still working on the premise that an hugely oversized skimmer will pull more DOS out than a properly size one and that is not true (IMO). If it did pull more out it would not be considered oversized any longer. The DOS is what breaks in the skimmer and simply put an oversized skimmer has a larger surface area to "slime" so it should take longer to break in using an undersized bioload.

jmaneyapanda wrote: You mentioned that larger skimmers have to be "dialed in" for the proper flow. But medium sized ones do not?

Every skimmer has to be dialed in, but manufactorers build skimmers for a certain bio-load and gph. If your tank matches that or is close, it is less "tweaking". Getting good skim isn't a plug and play process (if it were this discussion would be moot). Using a skimmer that is way higher than the bio load is likely to cause you more work. Not in every case as each skimmer is different, but it won't likely be as easy as one built for the systems flow and bioload.

At any rate, even if they are just as easy to setup and dial in there are several other reasons I have mentioned to not use a hugely oversized skimmer. The extra heat and price alone should steer someone well clear of them.

 

[jmaneyapanda]

Straegen:

Through my experience, and evolving understanding of this biochemical process, I must respectfully disagree with your assessements. Perhaps I dont understand your point. What do you mean by "properly sized" and "oversized"? In my definition, there cannot be an oversized. But you claim there can be. BY whose standards? The manufacturer or retailer?

Why would turn the skimmer off? I run mine 24/7, and recommend everyone do the same. The only time it's off is when I'm cleaning it. But, regardless, no matter what skimmer, when turned off, anything in the skimmer neck will return to the skimmer body. It makes no difference if you "throttle it up". Once you restart the skimmer, it will refoam that material.

While bioload helps to acclimate the skimmer, I do not think it will occur any slower in a large skimmer than in a small. You have claimed that recirculating in a skimmer makes no benefit to skimming. This is the exact principle that the highest end skimmer utilize to maximize skimming. The more frequnetly the water passes through the skimmer, the more dissolved organics gets pulled. For example, if a skimmer pulls (hypothetically) 50% of the organics per pass, it will incrementally get more and more of the dissolved organics for each pass. So recirculation increases skimming capacity. The only case where this is not true, is if you assume the first pass gets 100%. Which is not realistic. So using your exmple, let say a "properly"ized skimmer circulates the tank once per hour, and the "oversized", ten times per hour, the normal skimmer would get (hypothetically) 50% of the organics. The ovresized would get 50% the first pass, and the 50% of that remaining 50% the second, and then 50% of that the third, and so on. It would take out far more organics.

I think manufacturers make different model skimmers for economical reasons more than functional reasons. They can sell a $50 skimmer for a nano easier than a $500 one. But would the $500 jumbo skimmer work better? Without a doubt. This is the principal I dont think you are quite understanding. It is the physics of the matter.

Once again, I do agree, it is not necessary to run a huge skimmer on a smaller tank, but I must argue that such larger skimmers are more effecient and no more work than such small ones.

 

[gclackum]

I just hooked up my skimmer @ the sump. I am getting skim, and it is lovely. My Nitrates have been staying around forty (prior to skimmer). What do I really want them to be? I have softies; leathers, xenia, zoas, polyps etc.. I also have one 3" clam (brand new), fish and favites. I have heard that clams will drop your Nitrates. I'm sure my one want make any difference, however I have PCs so I wanted to see how it would do. I would be very interested to get your input on proper nitrates.

 

[cameron]

jmaneyapanda wrote: Once again, I do agree, it is not necessary to run a huge skimmer on a smaller tank, but I must argue that such larger skimmers are more effecient and no more work than such small ones.

You have the last word on the subject. Maybe we can crank the debate back up after a meeting with some others over some food sometime.

 

[johnqx4]

jmaneyapanda wrote: Lets say I put a skimmer rated at 8 million billion gallons on a 10 gallon tank. Over time the foam will build and build, and build in the neck. But it probably wont reach the skimmate cup for A VERY LONG TIME! But that skimmer is still removing the wastes just as good as it would on a 8 million billion gallon tank. It is just accumulating less.

I think you answered your question (or at least the point others were trying to make). Using the above skimmer (this is absurd but very useful), you would probably pay a thousand dollars a day for the electricity, and your flow would be similar to a tidal wave. The skimmer would skim, but the wasted resources would be astronomical. Where as, a small air driven skimmer would do the job just as well not affect the water flow, and cost two bucks a year to run.

Obviously the comparison is absurd, but because of that it works. This is somewhat similar to an air conditioner. ALWAYS, get the right size for the room. Bigger works, but it cost more in the long run and causes problems with humidity etc...

Things are sized for a reason (not always correctly, but for a reason)

My $.02 worth

johnny

 

[jmaneyapanda]

Well, one last word, then I will clam up. Please understand, I am NOT trying to say that everyone should go out and buy the largest skimmer they can fit into their house. I was merely commneting on the fact that people have claimed that larger skimmers are harder to operate, and that larger skimmer wont do a better job than smaller skimmers (on any sized tank).

John- I appreciate your analogy, but I dont think it is quite applicable. With a room air conditioner, you are correct, if you oversize, it will do the job, but at a trade off for power consumption. But there is a measureable, and empirical, endline. We want the room to be 68 degrees F. There is no such measure for skimmer function. So, arguably, the tank could always use a little more foam fractionation. See Mojo's comment on this earlier. If we want our tanks to be as clean as they can be (practically), the larger skimmer will do a better job. Yes, my example was intended to be extremely outlandish, but it was to prove the point that the larger skimmer will operate just as easily, and likely more effeciently, than a "properly" sized skimmer.

 

[cameron]

OK I can't shut up... it is a problem and I am seeking help.

jmaneyapanda wrote: the larger skimmer will do a better job. Yes, my example was intended to be extremely outlandish, but it was to prove the point that the larger skimmer will operate just as easily, and likely more effeciently, than a "properly" sized skimmer.

Not true. A larger skimmer does not mean you will get more DOS if you are already pulling near max DOS out of a tank. A larger skimmer is not necessarily going to be more effective. There is a point where a skimmer that is ridiculously sized will not pull any more crap out of a tank than a good smaller sized skimmer. There is only so much DOS that can be extracted. I will grant you it takes an extreme example, but that is what we are talking about here. A retardedly huge skimmer on a small tank.

For example if you have two fish in a 20 gallon tank a Tunze 9020 isn't going to pull any more waste out of the water than the Tunze 9005. If you bought the Tunze 9020, you would spend 2.5 times as much on initial cost, generate 30W more heat and the monthly electric bill would be noticebly higher.

 

[jmaneyapanda]

Hey, I think we ahve the same affliction!!:doh:

Here's where I see the error in your assumption. You assume you are pulling out mear max out of the tank already. I honestly think you are overestimating a "properly" sized skimmer. I will get back to this. But here is the physics of my argument. Unless you tell me your skimmer is taking out 100% of the dissolved organics, my argument mathematically and realistically is correct. And I assume you are not claiming your skimmer can do this. Lets say you think your skimmer can take out 95% of the organics in a period of time. That means 5% stays in the water column. A larger skimmer on the same setup will process more water absolutely in the same period. So it will recirc maybe 2 or 3 times more over than the smaller skimmer. So, of that remaining 5%, it will get re-skimmed, and 95% of that remaining five percent will get taken out that 2 or 3 more times. Ipso facto, it will skim better. The only way I can see your argument as being correct, is if you claim your skimmer is pulling out 100% of the organics. You are not claiming this, are you? I can guarantee you that almost any skimmer will not make this mark.

Here is my INTERPRETATION of skimmer sizing. Manufacturers make this so they can sell smaller models as well as larger models. I feel these ratings are rather arbitrary. Look for yourself- most retailer sell them under the following premises- "Skimmer x- for tanks from 500 gallons to 2000 gallons". See this link:

http://www.marinedepot.com/aquarium_protein_skimmers_aquac_ev.asp?CartId">http://www.marinedepot.com/aquarium_protein_skimmers_aquac_ev.asp?CartId</a>=
How is it possible to have a skimmer ideal for 500 gallons and 2000 gallons? Those volumes are so different (300% different actually), that how can it pull out maximum organics on both? It is not possible, the manufacturer has deemed it so to be able to sell it's multiple models, and to minimize the consumers "overkill dilemma", as described earlier. But would this skimmer work on a 40 gallon tank- yes. Would it pull out more organics than a skimmer "rated" for a 40 gallon tank? You better believe it. Because no skimmer can pull out 100% of the organics.

 

[cameron]

Comparing manufactorer ratings is difficult to impossible. You can get the biggest crappy skimmer and it won't do what a good smaller skimmer can do. So at any level our debate is theoritical at best since you can't really compare without running the tests. However I firmly believe that in my extreme example 2 fish in a 20 gallon tank (nothing else), both Tunze systems the 6020 and the 6005 pull nearly the same amount of waste in the same time. Both skimmers are just more powerful than the total amount of waste in the system. They will both way overskim the system and at some point you get a diminishing return to the point of absurdity. A larger skimmer can't pull out what isn't there.

I would also add as the bio-load increases the more difficult it is to get a skimmer too large for skimming purposes. I still believe it is best on the wallet and the heat output to have a properly sized well built skimmer at any rate.

 

[wbholwell]

I can't resist on jumping into this thread . Here's my 2 cents on skimmers and their ratings:

No skimmer is 100 percent effective at removing all dissolved solids in the water. Let's say for argument's sake that we have a skimmer that's 99% effective, meaning that if we have a static volume of polluted water (nothing is being added to it like in a real-world reef tank) it would only remove 99% of the dissolved solids. That remaining 1% would stay in the water no matter how long it skims beacause for our hypothetical skimmer 1% is not enough to create enough surface coheasion on the bubbles so that they do not burst.
Comparing two skimmers of the same effeciency but different sizes, the larger would remove the polutants faster because of it's higher flow rate, but both would only remove 99% of the pollutants. In a real-world situation if the smaller skimmer can remove the pollutants faster than the tank can produce them then there would be no advantage in having the larger skimmer with the same efficiency. I believe, however, that a good skimmer is efficient due to A) a small bubble size and B) a long bubble-water contact time. And so, because larger skimmers of the same design generally have longer tubes and hence longer bubble-water contact times I believe they are more efficient, and that's what matters.

 

[cameron]

To get this straight... you guys believe that in my example (2 fish 20 gallons) the Tunze 6020 actually pulls more waste out than a Tunze 6005 in the same time frame? I don't think it will and even if it does, the amount is an amazingly small percentage probably immeasurable. Two fish can only produce so much waste and both skimmers are going to skim the hell out of that water.

We aren't talking about a skimmer that is oversized, we are talking about a skimmer that is hugely oversized.

 

[johnqx4]

jmaneyapanda wrote: John- I appreciate your analogy, but I dont think it is quite applicable.

Well, Never let it be said that I need to be applicable to jump in on a thread...

However, all things being equal (they usually aren't)... And, the fact that you can only extract so much blood from a turnip (unless you are the IRS)... Getting a larger skimmer (in real terms, not a 1/10th of a percentage point in DOS removal) will really only benefit you if you move to a larger tank and can thus take your equipment with you.

In the mean time, you have larger, louder and more costly to put up with...Where is the value?

johnny

 

[jmaneyapanda]

Once again, let me make the claim- I am not saying everyone should go out and get a huge skimmer. I feel the opposite, because of many of the reasons stated, such as energy consumption, setup costs, etc. BUT... please do not make the claim that the larger skimmers are not better at skimming smaller tanks- this is untrue. This is the only point I am arguing.

Straegen- I cant comment on the Tunze, I have no experience with them. But as per your example, the larger skimmer should be able to pull out more organics. Perhaps it will be a small bit more, or even negligible to the naked eye, but if it is capable of skimming faster and larger scale, it will skim better. Is it worth it for the extra power consumption and extra cost? Probably not. But will it pull out more? All things considered- yes. Unless you want to make the claim that the smaller skimmer is pulling out 100% of the organics (which I assume you are not claiming). If, in your example, they are pulling out the same amount of waste, they are both proportionally sized to the organics of the tank. Lets incrementally bump up the organics until the larger starts outperforming the smaller noticeably or substantially. Why did this happen? Because the smaller cannot skim as well as the larger. But does the performance of the larger get better as the tank volume grows- no. It will if anything, pull out less of the organics as the tank grows, not more (because it is not getting as thorough a turnover as when it was smaller).

Lets look at it another way. Hang on power filters- One with 100 GPH and ones 400 GPH (same manufacturer, just larger "sized" models). Which one will work better on a equal tank? The larger, right? It is the same principle.

Now I agree it is likely better on the wallet and energy bill to not significantly "oversize" the skimmer, but that is not what we are discussing here. I have always agreed to that.

Wbholwell- I am defining effectiveness differently than you. You say that 99% effective means that 1% is incapable of being skimmed out. My definition is 99% effective is 1% capable of being skimmed, but being missed due to random variation of the tank and dilution theory. In my definiton, higher flow(effecient) skimmers would take out more arganics, as it would get more chances than the smaller. I agree with your comments on effecnciency- the bottom line is, the more water than can contact bubbles, the better the skimming, whether it be through duration, bubble amount, bubble density, or any combination. Otherwise, I think we're in agreement.

John- you are correct, I am not claiming a larger skimmer may double the output or anything, but I will claim it will be better, to whatever degree. The comparison of the two would be totally dependant on those two skimmers and the water. Reagrding value- this is not my argument. I agree, it may not be more valuable- but it will be more effecient.

 

[cameron]

jmaneyapanda wrote: please do not make the claim that the larger skimmers are not better at skimming smaller tanks- this is untrue. This is the only point I am arguing.

I don't believe that was an issue for debate at least for me. I simply stated that overskimming is impossible (I think we all agreed on that with some specific exclusions), that and I am quoting myself "You want to find a skimmer that is sized appropriately to your system or one that is very easy to adjust." as some large skimmers don't have gate vavles or can be difficult to setup in a small sump, and to quote again "The focus should be on the design of the water flow, pulling water into the skimmer from the correct place and making sure you don't have a skimmer too small." which again I think we can agree on.

Your original dispute with a statement I made later was quoting me (yet again)... "It isn't that you can't get a good skim out of a skimmer too large for the system, it just takes more adjustment (generally speaking). That said there are some skimmers that are huge and have excellent adjustment capability that could work on even the smallest systems."

At no point did I say you wouldn't get as good a skim from a larger skimmer. I think you would.

The point we seem to disagree fundamentally on is that there is some point where an oversized skimmer is skimming as well as a hugely oversized skimmer. I don't think short of a live test either of us will budge on that one.

The other and I am not sure how we disagreed was from my statement that some large skimmers are built for a certain bio-load and flow and are more difficult to adjust with smaller bioloads and possibly smaller flows (those without a gate valve... such as the larger ASM skimmers come to mind), but there are some large skimmers that are easy to adjust and aside from heat and price will work just fine. I am not sure how we disagreed, but I think it was in there somewhere.

jmaneyapanda wrote: But as per your example, the larger skimmer should be able to pull out more organics. Perhaps it will be a small bit more, or even negligible to the naked eye, but if it is capable of skimming faster and larger scale, it will skim better.

This would require a live to test for either of us to be satisfied I believe. I just don't think there is that many organics produced by two fish in a 20 gallon tank for either skimmer to miss much. Again, this is a fundamental difference of opinion and I don't think either of us is going to budge without some provable numbers.

jmaneyapanda wrote: Unless you want to make the claim that the smaller skimmer is pulling out 100% of the organics (which I assume you are not claiming).

I believe the fish and other parts of the tank are constantly excreeting waste and such so that a skimmer will never be done doing its job. However, I do believe that the smaller Tunze will pull out 99% of the waste in roughly the same time the larger Tunze will pull 99% of the waste out on a tank that small. They are both so massive and the turnover so complete that they are going to pull whatever could be reasonably pulled out quickly. There probably is some difference, I would just argue that it isn't noticeable on any level from the health of the fish to the measurements of the water itself. I believe in a blind study, the amount of skim and water quality will be nearly identical between the smaller skimmer (which is still oversized for the tank) and the massively oversize skimmer.

jmaneyapanda wrote: But does the performance of the larger get better as the tank volume grows- no. It will if anything, pull out less of the organics as the tank grows, not more (because it is not getting as thorough a turnover as when it was smaller).

I believe this is wrong in a certain aspect. If a skimmer is pulling 2 cups of skim a day and you increase bio-load in the tank, it isn't going to pull out less than 2 cups the next day. It might pull out the same because the skimmer is at capacity, but it won't pull out less. If you increase the water capacity of the tank and thus reduce flow, then yes you are probably going to get less skimmate. However if you increase a 20 gallon to a 25 gallon, bio-load remained exactly the same and you were getting a cup a week, you probably will still get a cup a week mainly because your supersized skimmer is still turning the water over a rediculous amount.

jmaneyapanda wrote: Lets look at it another way. Hang on power filters- One with 100 GPH and ones 400 GPH (same manufacturer, just larger "sized" models). Which one will work better on a equal tank? The larger, right? It is the same principle.

If it is a very small bio-load and the skimmers are both high quality, they will both work equally well when it comes to maintaining water quality. I also believe the skimmate will be nearly identical. Again, a fish can only crap so much. I know a skimmer can't get everything and fish continually crap but the speed at which it reaches maximum water quality can be obtained if both skimmers are sized significantly larger than what they are skimming even if one is much bigger than the other in roughly the same time (design elements being equal).

I need to copy this onto reef central and let some of those bio-chemist take a whack at this and see what they say.

 

[mwitten]

OK, can't resist jumping in on this thread...

First, let me say that I have had, since 2003, 7 skimmers (My T1000 came with another used tank, and have never used it). I started with a brand X that never worked at all... Moved to an Aquamedic, I think (not sure) and finally to an AquaC Urchin. All this was for my 58... Seemed like a good size range (150 gallon rated for these) and all but the first worked fine.

I had a small (30g) tank with a Remora. Seemed to work OK.

For my 120+58 combined to basement sump system (about 240g real capacity, all told), I got a MRC-2 a few years ago. I upgraded it to two of the new injectors a year or so ago.

About 6 months ago I went to a Deltec 702 in serious frustration over nitrates and maintenance, as I was on the road a LOT and just could not put the time into the becketts. I think this will be the last skimmer until I pay off the mortgage..

My observations from use, research, and a few wild guesses:

They all work a LOT better when I clean them regularly. Ditto on adjustment.

The bigger ones SEEM to allow for a bit more neglect.

Some folks, like me, turn them off during feed cycles. At this point, anything in the column, box, etc. is returned to the tank (except what is stuck to the sides).

I can safely say I am overskimming the heck out of my tank, and my leathers and clam are doing just fine.

50 lbs of new live rock added to my sump did a lot more to take down the nitrates than my skimmer upgrades. Also a lot more than the sulfur reactor I built as well.

Smaller vs bigger adjustments? My tuning always seemed more dependent on what stupid things I had done with the tank/chemistry/additives, etc. than with the size of the skimmer. I do run the 702 a bit higher in the column than recommended, but once set, I pretty much leave it. Note that it took me a few years to figure out that putting my hands in the water had an almost instant effect on the skimmer..

I have also seen long threads on how things like "dwell time" (how long water spends in the skimmer), sump turnover/recirculation rate, Purigen, loading (amount and type) and many, many other things impact skimming, not to mention particular technologies (Beckett, venturi, etc.).

My personal thought is that, while you might be able to undersize a skimmer (note that I am assuming your tank is setup needing a skimmer... no experience with skimmerless tanks here) I suspect there is a huge range of "right" sizes, and that a lot depends on numerous other factors.

Ditto efficiency, though (as has been covered) there are many kinds of efficiency... skimming capacity versus energy, noise, cost, size, required upkeep, possibility of skimmer-related disasters, etc. all come to mind.

Too long... cutting myself off now.

-Mike

 

[jmaneyapanda]

Straegen- perhaps I didnt understand your veiwpoint. The main argument I was making (at least recently) was against this quote of yours, from post #22. "A good skimmer that is appropriately sized will pull about the same amount of DOS from a tank as a larger one. Size does not equal effeciency and you can only pull so much out of a tank based on bio-load. Larger does not equal better which is the round-about point I have been trying to make."
I dont agree with that point, and I was going on the premise that you felt a larger skimmer on a smaller tank would not skim better than a smaller. If I have misunderstood, I apologize.
I must say though, I dont quite understand your "oversized vs. massive oversized" argument. What is the difference. The same principles and operation. I dont think you'll need live tests as you claim. Why do the higher rated skimmers work for larger (in vloume and bio load) tanks? Because they are more effecient at removing organics. Whether it is higher flow, or more bubbles, or better bubbles, or whatever, they are better at getting out the organics from the water per standard time. Otherwise, people could just use a Red Sea Prism and empty the cup 50 times a day. agin, using your 20 gallon example, would the tunze pull out more than a Red Sea? Why? This is the argument I am making. I guess if you are saying one skimmer will pull out at 99.998% and the higher power will pull out at 99.999%, I will agree. Yes the diffrenec would be small- but it is there. It is small because of the proportions of the skimmer to the tank. Again, If I misunderstood your argument, it is my bad, and I apologize.
Please reconsider my example of "the growing tank". If a skimmer is pulling out 2 cups a day, and you increase the volume of the tank (say from 200 to 300 gallons), do you think it will still pull out 2 cups (assuming all bio load has remianed the same? It will not. Because its operting rate will stays the same, but the volume has increased, so it will not process the same percentage of the water primarily or redundantly. A little clearer, if the skimmer has a pump which is 300gph on a 150 gallon tank, it will process the water twice in one hour. Increase the size of the tank to 300 gallons. It will only process the water once per hour. So, unless you will claim your skimmer can pull 100% of the organics out in one pass, the effeciency has decreased. Backs this example down to 10 gallons, will the skimmer still operate at the same rate? Yes. back it down to 1 gallon, will it still be at the same rate? Yes. Will it work any less effeciently than a red sea? Absolutely not. My point is just a skimmer that work well on a big tank, works just as well on a small tank.

If I am just rambling, and we are on the same page, let me know, and I will stop.

 

[cameron]

jmaneyapanda wrote: If I have misunderstood, I apologize.

No need to appologize. The way it is written certainly states that, but I was starting to get short handed after typing so much. I was referencing a skimmer that is oversized versus a skimmer that is hugely oversized for the bio-load. It gets back into the core debate where we disagree about how much bio-load skimmers can pull out.

jmaneyapanda wrote: I must say though, I dont quite understand your "oversized vs. massive oversized" argument. What is the difference. The same principles and operation.

I believe that there is a diminishing return and that some point two skimmers one smaller one larger but both considered oversized will return basically the same skim amount in roughly the same time frame since they are skimming ahead of newly created DOS. The way I understand your point is that no skimmer can ever get ahead of the DOS created in a tank. We just disagree on this and I would have to see some numbers before I believe an oversized skimmer is less effecient than a largely oversize skimmer.

jmaneyapanda wrote: I dont think you'll need live tests as you claim. Why do the higher rated skimmers work for larger (in vloume and bio load) tanks? Because they are more effecient at removing organics. Whether it is higher flow, or more bubbles, or better bubbles, or whatever, they are better at getting out the organics from the water per standard time.

Again, I think that in my example (2 fish 20 gallons 6005 vs 6020) both skimmers skim 99% of the DOS out of the system quickly because there just isn't that much bio-load. Any new DOS gets sucked into the cup almost immediately. I don't think with a super low bio-load and cycling the tank 50 times versus 100 times is going to yield measureable results in water quality and skimmate quantity.

I just believe at some level say turning the tank over 1000 times versus 1000000 times isn't going to yield DOS that isn't there. At some point a skimmer will keep up with DOS in the tank if the skimmer is big enough. If I created a skimmer as large as the tank and skimmed the entire tank every second, it can't take out fish crap and uneaten food that isn't there. Skimmers can't invent skimmatey the have to extract it from the excess nutrients. Once they strip those out, they are skimming clean or virtually clean water.

That said as you increase the bio-load, it becomes harder to get a diminshed return. Bio-load calculations seems exponential more than incremental.

jmaneyapanda wrote: Otherwise, people could just use a Red Sea Prism and empty the cup 50 times a day. agin, using your 20 gallon example, would the tunze pull out more than a Red Sea? Why?

Apples and oranges. First, a Prism is never oversized even on a 5 gallon tank. Second, it is a poorly performing skimmer. I am talking about comparing a skimmer that is clearly pulling most of the skimmate out of the system versus one even bigger than that. Comparing a skimmer that is at or nearing capacity is not the comparison I have ever made. I would love to see how much better a Tunze 6020 versus a 6005 does on the same small tank in the same interval as they are the same design and they are both likely pulling the DOS about as fast as it is created. If the 6005 doesn't pull the same skimmate, you would be right. If it does pull the same skimmate, I would be right.

This is the argument I am making. I guess if you are saying one skimmer will pull out at 99.998% and the higher power will pull out at 99.999%, I will agree.

My point is they are going to pull nearly the same because they are staying ahead of nutrient creation in the tank. A bigger skimmer can't pull what isn't there. I can't argue that a bigger skimmer reaches this point faster, but once both skimmers are ahead of the waste production they are pulling virtually the same skimmate out of the system from that point forward.

Please reconsider my example of "the growing tank". If a skimmer is pulling out 2 cups a day, and you increase the volume of the tank (say from 200 to 300 gallons), do you think it will still pull out 2 cups (assuming all bio load has remianed the same? It will not.

Agreed because flow through the skimmer has decreased. However, riddle me this... 2 small fish, 20 gallon tank and 10 gallon sump. You are using a monster skimmer say a MR-3 which is pulling out 1 cup a week of skimmate out of the tank. You switch to a 20 gallon sump and add 10 gallons of saltwater. How much skimmate is your MR3 going to take out of the system? I bet 1 cup a week. I believe at some point a skimmer reaches a saturation point. That takes one big skimmer, but that is what we have been talking about all along. A huge skimmer versus an even bigger skimmer.

If I am just rambling, and we are on the same page, let me know, and I will stop.

As for me, I am having fun. I like debating especially on a topic we 99% agree on.