Beckett vs. Needlewheel skimmers

"What protein rich layer?"

Well, you know that whole process where proteins are attracted to the air bubble's surface? Well, the same thing happens on the surface of your aquarium... oils, proteins, etc. May proteins are lighter than water as well (and some not so light), but yes, the upper most layers of a tank are the richest in proteins. HOB skimmer users all know about the performance gain they get from keeping the skimmer/pump intake as close to the surface as possible... its no secret. But if your turnover is too high, this accumulation never has a chance to take place... the surface layers are shot through the overflow and back through the sump return to the tank where they get plended back into the tank's water column.

If you want more info, Calfo is at the Marine Depot forums and Im sure he wouldnt mind telling you about his long linear overflows, low-flow sumps, and direct feed skimmers. He's a huge advocate of all of them.
 
Spazz, what's Bill feeding that Aquarium? Gucamole & chips? it looks like skimmate from mars.

Two extremes again, or...?
Noswhag water changing skimmer wet skimmate.
and
Bill's Gucamole would fall under the Dry skimmate catagory.
 
Well, you know that whole process where proteins are attracted to the air bubble's surface? Well, the same thing happens on the surface of your aquarium... oils, proteins, etc. May proteins are lighter than water as well (and some not so light), but yes, the upper most layers of a tank are the richest in proteins. HOB skimmer users all know about the performance gain they get from keeping the skimmer/pump intake as close to the surface as possible... its no secret. But if your turnover is too high, this accumulation never has a chance to take place... the surface layers are shot through the overflow and back through the sump return to the tank where they get plended back into the tank's water column.

You keep ignoring that I recommended a big skimmer to process all or nearly all of the overflow water. Obviously then, it would not be "shot through the sump".

Yes I know proteins accumulate at the surface, I've mentioned that already. And yes I know that HOB users get more performance from surface skimming. And yet again you ignore the fact that most people take surface water anyways.

I don't know how you are getting this "stratification" of proteins unless you have no circulation in the tank. If pointing a powerhead at the surface will break up surface scum, stuff that is already "bonded", then I have no idea how these "lighter proteins" would stay in a nice neat layer with any sort of flow inside the tank.
 
<a href=showthread.php?s=&postid=8451479#post8451479 target=_blank>Originally posted</a> by JC VT
Can you show where it is incorrect? Throwing a vague statement out like that seems like you're trying to discredit him, and his statement, without bringing anything to the table.

This is waste removal... for a reef tank. SPS need clean water, we know that. How do we get clean water? Waste removal :cool:
Click to expand...

Of course its waste removal.. Exactly what I said it was. I was just saying that the established principles of waste removal carry more weight than he does here.


"Reskimming the water would be the best way to have the effluent as low in organics as possible, but it won't end up with the tank being lower in organics."

I say, prove it. If a skimmer that reskims can take something out that a single pass skimmer can't then hes wrong.

Its all an issue of curves. The only case in which he is correct, is if the skimmer is undersized.
 
I was just saying that the established principles of waste removal carry more weight than he does here.

What do the established principles of waste removal say?

I say, prove it. If a skimmer that reskims can take something out that a single pass skimmer can't then hes wrong.

No, it doesn't mean he's wrong. His argument is having the highest level organics in the skimmer as possible, giving the greatest protein skimming. More organics, exposed to more interface area gives greater skimming. His argument is sound. Matching the highest level organics with the agent to clean it.

What is this "something"? Is it something we should worry about? Is it toxic? Does it even exist?? Does anything in our aquariums care (if it exists at all), whether or not it is skimmed out immediately or not?
 
Again though, you're making the assumption that high flow skimmers have equal efficiency rates as low flow ones. The higher the flow, the lower the contact time, and the lower efficiency.

Again, we're talking turning your tank over X times at hour at Y efficiency vs turning your tank over A times an hour at B efficiency.

Is XY greater than AB? He's saying yes, but giving no evidense as to why.

Again, yours/his argument is based on the idea that a skimmer with low turnover wont be able to keep up with the tank, and organics will accumulate faster than they can get to the skimmer. This is simply not true. The faster you move water through a particular skimmer size, the lower the contact time gets.


We're trying to maximize bombardment rate here: IE Contact time for protien against bubble times amount of times a protien is exposed to bubbles.

As to contact time, theres no argument that can be used to dispute that lower flow adds to higher contact time. As to exposure occurance, the difference in high flow and low flow is this: In a recirc skimmer, a protien gets exposed to a bubble now, and repeatedly exposed now. In a high flow single pass, it gets exposed now, and in 20 minutes, and again 20 minutes after that.


Your whole "More organics, exposed to more interface area gives greater skimming." Argument stems on the idea that theres going to be a significant difference between water thats run through a high pass skimmer once and the water the skimmer was getting. I think thats false. If thats was the case, a skimmer with 800gph pump on an 80 gallon tank would have the cup full and have shut itself down because of lack of nutrients in less than an hour.


That doesnt happen... why? Because the water is pretty damn clean in most cases, and the important thing is htat a skimmer can pull out whats left, and that takes lots of contact time. Unless your skimmer is way undersized, and flat out can't keep up, efficiency is more important than amount of water processed.
 
Again though, you're making the assumption that high flow skimmers have equal efficiency rates as low flow ones. The higher the flow, the lower the contact time, and the lower efficiency.

And keeping dirtier water in the skimmer is way more efficient than scrubbing. Higher level of organics paired with the agent to remove them.


In a recirc skimmer, a protien gets exposed to a bubble now, and repeatedly exposed now.

While the other millions of proteins are sitting in your tank, waiting in line like they're at the DMV. And its not like a molecule is not repeatedly exposed to bubbles no matter what kind of skimmer you use.

Because the water is pretty damn clean in most cases, and the important thing is htat a skimmer can pull out whats left, and that takes lots of contact time.

What's your logic that the remainder takes alot of contact time?

What is this "something"? Is it something we should worry about? Is it toxic? Does it even exist?? Does anything in our aquariums care (if it exists at all), whether or not it is skimmed out immediately or not?
 
Not to take sides, that is not my intention here, but I dont see this argument at present developing anywhere. You both have to step back and establish what you both accept as truth, and build from there. I gave my three reasons a while back, leaving out the arguments of recirculating contact time's possible relation to dwell time, ORP, and skimming directly from the surface... not to mention the lower wattage of needlewheels.

Perhaps it would be a good idea for everyone to take a step back, and on those issues that are disputed, actual research or seeking out an expert opinion might be a good idea. Calfo, Shimek, Holmes-Farley are all at our disposal and Im sure have some responses for us. I would only suggest that that information be applied better than that tangent from the chemistry forum posted earlier.

Otherwise, you two are going to get worse and worse.... I can already see it... and this thread will close just like a DSB vs. BB thread.
 
My ORP dropped 100 pts. when I raised my skimmer 4". I believe raising it caused the flow to slow since it is now so close to the bottom of the overflow. I am going to cut the BH that is blocking it and lower it back down. I never would have guessd that the ORP would react so much to such a small adjustment.
 
A deep breath is almost always a useful thing. And suggesting that experts be consulted on disputed facts has a long tradition of working well. But that's what started this latest excitement. An expert (Randy) was consulted and he said a few things that challenge some obviously deeply held beliefs. While I don't understand the tangent of some earlier posts, Randy clearly expressed his doubt about dwell time and the concept of reskimming the same water vs. using the dirtiest water. Specifically-

I also think maximizing dwell time is misleading and may be wrong, depending on how it is thought of. If you have the same total surface area of bubbles in contact with the water inside the skimmer, the replacing those bubbles with fresh clean surfaces may actually give better skimming action than leaving the original bubbles in place longer.

I am sure this is a disturbing comment for those people that have hung their hat on a different viewpoint. Randy did briefly explain his reasons for his judgment and while he may be wrong, as all mortals are at some point, his perspective carries more weight with many of us than uncredentialed opinions.

Some of this also likely comes back to how well the skimmers you have personal experience with are designed and engineered. It is clearly harder to design a skimmer that does a good job of processing lots of air and water than one that processes lower amounts of air or lower amounts of water (or both). For lower amounts of water (for example) it may be true that some commonly used skimmers work better at those low flow rates and work more poorly at the higher flow rates. But just because a particular skimmer has a suboptimal design does not mean that slow flow, or reskimming, or your own particular favorite truism is a scientific fact.

It's interesting that Randy specifically said that "maximizing dwell time is misleading and may be wrong" and yet a number of people have continued to cite the greater dwell time of their approach as their facts as to why Randy is wrong.

But back to a call for more experts. I think this is good. Can we have a short discussion as to which experts might be as good or even better than Randy since asking less knowledgable experts seems like the wrong approach. Who are other experts that know the science of protein skimming well enough to comment on these specific issues? Big names are not enough. They should have creditials in this field behind them. I do not think simply keeping lots of aquariums or having 10+ years of reef experience qualifies one as an expert on this topic. And anyone that makes generic references to Escobal as a justification for their viewpoint should be disqualified.

Who are the other experts that we could ask to add their views on this subject?

Al
 
one problem is see is the variances in tank conditions/setups prevent any certainty in application of the science of protein skimming. i imagine that the variety and behavior of proteins is tank specific and maybe even time of day specific, and certainly not extendable to other systems.

one statement i offer as fact is that the water in coming over the overflow is the dirtiest water in the tank; that is why we skim the surface. beyond that i can only offer my observations

i currently run a asm g3 on a 90 and a beckett on a 180.
both skimmers do the job and keep the tanks looking good, and both have some nasty cups to clean out;

the g3 is being fed directly from the overflow, my return pump is a eheim 1250 with apx. 4 feet of head, and i estimate im getting close to 200 gph through it, which most would consider low flow, which i find super quiet.

the beckett was being driven by a mag 18, now a genx 55? something; the mag 18 broke two weeks ago, i had been running without a pump since, but since yesterday having this pump is raising my temp 3 degrees over the day. i don't run a chiller, and won't, so something has to give.
the heat required with a pressure rated pump is forcing me to switch to a needlwheel, perhaps an ati bubblemaster (waiting on some reviews)

imo one is not inherently better than the other, and my plans for a larger tank will likely include two skimmers, one beckett, one needlwheel.
 
twon8 can you tell me a little about how your cooling your system currently. i may be able to help. you might not have to spend a ton of money replacing that skimmer if its working for you. if you dont have very many fans blowing across the top of the water that in itself would help to keep the tank cool. just a thought.
 
<a href=showthread.php?s=&postid=8459520#post8459520 target=_blank>Originally posted</a> by jnarowe
My ORP dropped 100 pts. when I raised my skimmer 4". I believe raising it caused the flow to slow since it is now so close to the bottom of the overflow. I am going to cut the BH that is blocking it and lower it back down. I never would have guessd that the ORP would react so much to such a small adjustment.
Click to expand...

That does comfirm my suspicion... or at least make it worth looking into more. I know that the longer water is exposed to air, in theory, this should raise the ORP... and raising the ORP should increase the skimmate output. That be a valid reason for the performance of recirculating skimmers being so much greater... possibly. Interesting.

As for Randy's comments that I feed were 'bent' and taken out of context...

NOTE: He said he sees no benefit to re-skimming the water. That does not mean he sees no benefit to a recirculating skimmer. The ability to use a much larger pump, throughput control, better performance due to elimination of back pressure with any pump, the ability to use the skimmer in a countercurrent manner (single-pass designs cant be counter-current by nature, and counter current is the best), etc... these are all undisputed reasons why a recirculating skimmer is better... without even considering the effects of the extended contact time's relation to making up for dwell time, the higher bombardment rate ( I knew there was a term I forgot, thanks Rich), ORP, and direct overflow feed. Right there, those 3 design features of a recirculating skimmer alone trump anything else that can be argued with a single pass skimmer. 3 facts that nobody needs to consult an expert on. Also, consider how much taller you can run a recirculating skimmer than a single pass because you have eliminated the water's back pressure on the mixing pump. The AquaMEdic T5000 Twin that is 6' tall wouldnt work at all as a single-pass skimmer... but as recirc. So with the same pump on a recirc skimmer, you can run a taller skimmer, which directly increases the dwell time... no doubt about it. Make that point #4!
 
Lets look at that list Hahn-
  • The ability to use a much larger pump: Bigger is not always better, and you like to mention Watts quite often, so I'd say point NOT proven.
  • throughput control: Yes, but no-one has proven that a certain throughput is better than any other. NOT proven.
  • better performance due to elimination of back pressure with any pump: True, but significant for needlewheels only.
  • the ability to use the skimmer in a countercurrent manner (single-pass designs cant be counter-current by nature, and counter current is the best): But that is exactly the point that Randy is debating. Not proven.
    So with the same pump on a recirc skimmer, you can run a taller skimmer, which directly increases the dwell time: True, and probably better, but I'd not carve that in granite.
So yeah, there is a lot of things to dispute in your "undisputed reasons why a recirculating skimmer is better".
 
No, All Randy said was that he doesnt see the value in 're-skimming' the water... as in, if you had two skimmers in parallel vs. two running in series. This does not take into consideration the performance gains from the design of a recirculating skimmer. It doesnt even say anything about recirculating skimmers themselves because it doesnt take anything else into account, only that skimming the water 2x instead of once in a closed system wont do much if the throughput is 2x. I would agree with that. But this does not take any of the other design benefits into account.

Bigger, for most NW skimmers, is better... only they cant run that high of an output because then the microbubble problems arise. The goal according to escobal is 13% air saturation... single pass needlewheels have a hard time doing this... recircs do not. I suppose it is somewhat personal opinion, but I hardly find more to be worse in this case...its so far from 'too much' to begin with. Turbulence is this big bad devil that so many people fear, but becketts have worse turbulence than any needlewheel could possibly have and they still pull out loads of gunk... so in this case, I would say bigger is with rare exception, always better. Besides, all I said was 'the ability to use' a much larger pump as a benefit. This alone, without any other implication, is true. Using a larger pump on a single-pass skimmer results in a higher throughput and most likely... more microbubbles. The 'ability to use' a larger pump is still a benefit, and not debatable. If you want to debate the effect of that larger pump... well, thats a case by case basis because there are no 'extreme ideals' or absolute rules as you point out. And there still is the whole idea that recirc skimmers can be taller as well due to less back-pressure on the pump. If running recirc means I can get the same air throughput on a skimmer that is 6-12" taller... why not?!?!

Elimination of back-pressure happens with becketts/venturis too. Still, Becketts have more back-pressure from the injector compared to a needlewheel, so the benefits might not be as dramatic, but they will have that much more pressure going into their intakes if set up as recirc.

Randy said nothing about the use of counter-current skimming in talking about recirculating. I think you are getting your terms mixed up or something...?? It is widely accepted that a countercurrent (this has nothing to do with the definition of recirculating) is more efficient than co-current operation, and single-pass skimmers dont even do that... the water doesnt even flow throught the entire height of the reaction chamber in either direction. Escobal's book, heck, any book will tell you counter-current operation is best. It extends bubble dwell time, increases contact ability, etc. And counter current is not possible with a single-pass skimmer.

I think those 4 points hold pretty well. If ORP and bombardment rate favor recircs as well... its just nails in the coffin...

I found a test in a German reefing site's archives that did a test of recirc vs. single pass. http://archiv.korallenriff.de/ Sorry, but a direct link is not possible with that site. The recirc does have a greater impact on ORP it turns out. Im going to finish reading/translating, and post. But the bottom line was that recirc skimmers were able to buffer ORP much like running ozone, and so they were able to grab more proteins.
 
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NOTE: He said he sees no benefit to re-skimming the water. That does not mean he sees no benefit to a recirculating skimmer.

So now we've gone from scrubbing everything out by reskimming to no benefit to reskimming? We can atleast agree that reskimming water at the expense of turnover is not a good option, right?

If running recirc means I can get the same air throughput on a skimmer that is 6-12" taller... why not?!?!

You mean like adding an extension onto a beckett skimmer? Why must it be a recirc?
 
Escobal's book, heck, any book will tell you counter-current operation is best. It extends bubble dwell time, increases contact ability, etc. And counter current is not possible with a single-pass skimmer.
Click to expand...


Randy's quote:

I also think maximizing dwell time is misleading and may be wrong, depending on how it is thought of. If you have the same total surface area of bubbles in contact with the water inside the skimmer, the replacing those bubbles with fresh clean surfaces may actually give better skimming action than leaving the original bubbles in place longer.

...

So contact time is not important, IMO. It is the amount of air/water interface present that is actually important, and the rate at which it is turned over. Increasing dwell time may actually increase the amount of air/water interface present, depending on how it is done, but dwell or contact time itself is not a key parameter (IMO).
 
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