Large diameter vs. small diameter skimmer necks
- Thread starter foshizzle
- Start date
RichConley
New member
Its really an issue of air draw. If the neck is too narrow for the air draw, it becomes almost impossible to adjust because the foam just wicks up the neck.
hahnmeister
In Memoriam
Well, its not just a matter of air draw. There are conflicting design philosophies on this one... some, like ATI/RoyalExclusiv/etc will tell you that a short and wide neck is better. Others will tell you that tall and narrow is better.
I can tell you about advantages/disadvantages of both. Perhaps the best is the funnel shape that Aqua Medic has a patent on.
I can tell you about advantages/disadvantages of both. Perhaps the best is the funnel shape that Aqua Medic has a patent on.
So let's hear em...
Seems a shorter, wider neck might require less cleaning from scum buildup? I've also noticed that with the 3" neck on my skimmer leads to more turbulence than I would like. Maybe a wider neck would produce a more stable foam head?
Would it be worth it heat form my own funnel neck?
Chris Witort
New member
There is no one best size neck. Each design will have different size needs. A large diameter skimmer producing large volumes of air will need a wide neck with a taller profile to accommodate the air flow without being overwhelmed and dumping everything into the collection area. This same big skimmer could work with a skinny neck and riser but would have to be turned way down. This of course would be wasting much of it's potential. A skimmer with a neck and riser that are too large has other problems. The foam head never crests the overflow point and extracts little to no skimate. It simply creates a sludge film on the neck and riser.
RichConley
New member
I'm gonna have to disagree hahn, I've never had a skimmer that was harder to tune than my turboflotor. I'm putting that up to the 1" actual neck diameter though.
Although, if you think about it, aquamedic's design isnt any different than anyone else's, its just at what part of the cone the neck attaches. The curve is below the attachment point in most skimmers, above it in theirs.
hahnmeister
In Memoriam
Was is a T1000 series or a T5000? I hate the 1000s... love the 5000s. The big thing about AM necks is that the curve continues all the way to the top of the neck. Most skimmers have a transition/funnel, but then continue in the cup with a pipe... no funnel. This is what Aqualine has a patent on.
I think one thing that is getting confused here is that nobody is debating that a neck that is too narrow will cause problems, but we have to look at the height as well. Lets clarify/qualify the question...
"If two necks have the SAME VOLUME, what are the advantages of a taller and narrower neck vs. a shorter and wider one?" I think for many skimmers, this is the make it/break it point. Look at how Spazz's volcanos have evolved in this respect.
Ill say that I GENERAL, a wider, shorter neck is better. BUT, I must qualify this by saying that if you go TOO WIDE, and you will have problems.
I find that the relative diameter of the neck depends on not only the air throughput, but the stability of the bubbles that the skimmer forms. Lets say I have an 8" diameter that is 4-5' tall with 1500lph of air going through it, and then a 12" diameter skimmer with 2000lph of air running through it that is only 18-24" tall. Which would get the wider neck? IME, the taller one, despite the lower air throughput. Why? Well, the taller one will make more stable bubbles that wont pop as soon as they hit the neck and condense. They will be stable and not drain as much on their way up because the proteins will stick to the bubbles better.
On the short, fat skimmer with more air... the bubbles wont be as stable... many will have short dwell times, and pop as soon as they hit the neck... Im just making rough numbers here, but lets say that despite the higher air throughput, the effective output compared to the tall skimmer will only be about 1000lph of the taller skimmer's output.
There are other things to consider as well. This 'bubble drainage' that happens with the foam as it dries is the reason why many skim wetter... to prevent the loss of as many proteins through drainage. A narrower neck hinders drainage, as all the air forced through a smaller neck means that the water is more likely to evaporate and exit the top of the skimmer rather than 'drain'. Drainage will be met with a tall, narrow path of bubbles to get around on the way down... not likely.
A prime example is a beckett... tall and narrow. The tradeoff is that the neck tends to get deposits more often.
The neck diameter/height does effect skimmer performance heavily, but it also depends on how the skimmer is designed to skim... wet/dry. Usually, if you want to skim wetter, a wide neck is better. If you want dryer, taller and narrower lends itself to that.
I think one thing that is getting confused here is that nobody is debating that a neck that is too narrow will cause problems, but we have to look at the height as well. Lets clarify/qualify the question...
"If two necks have the SAME VOLUME, what are the advantages of a taller and narrower neck vs. a shorter and wider one?" I think for many skimmers, this is the make it/break it point. Look at how Spazz's volcanos have evolved in this respect.
Ill say that I GENERAL, a wider, shorter neck is better. BUT, I must qualify this by saying that if you go TOO WIDE, and you will have problems.
I find that the relative diameter of the neck depends on not only the air throughput, but the stability of the bubbles that the skimmer forms. Lets say I have an 8" diameter that is 4-5' tall with 1500lph of air going through it, and then a 12" diameter skimmer with 2000lph of air running through it that is only 18-24" tall. Which would get the wider neck? IME, the taller one, despite the lower air throughput. Why? Well, the taller one will make more stable bubbles that wont pop as soon as they hit the neck and condense. They will be stable and not drain as much on their way up because the proteins will stick to the bubbles better.
On the short, fat skimmer with more air... the bubbles wont be as stable... many will have short dwell times, and pop as soon as they hit the neck... Im just making rough numbers here, but lets say that despite the higher air throughput, the effective output compared to the tall skimmer will only be about 1000lph of the taller skimmer's output.
There are other things to consider as well. This 'bubble drainage' that happens with the foam as it dries is the reason why many skim wetter... to prevent the loss of as many proteins through drainage. A narrower neck hinders drainage, as all the air forced through a smaller neck means that the water is more likely to evaporate and exit the top of the skimmer rather than 'drain'. Drainage will be met with a tall, narrow path of bubbles to get around on the way down... not likely.
A prime example is a beckett... tall and narrow. The tradeoff is that the neck tends to get deposits more often.
The neck diameter/height does effect skimmer performance heavily, but it also depends on how the skimmer is designed to skim... wet/dry. Usually, if you want to skim wetter, a wide neck is better. If you want dryer, taller and narrower lends itself to that.
hahnmeister
In Memoriam
yeah... its been the 'quote of the months' I like it so much. I just cant bring myself to delete it.
hahn since you seem to know alot about this issue would you mind taking a look at my thread and offer your input. i'm going to be moving my tank in the next month to a new house and i think i may use that opportunity to fashion a cone for the top of my skimmer. would you mind offering your advise to see if there is anything else you would recomend while i have the thing down and apart? right now my skimmer does a great job. tons of micro bubbles and alot of skimmate is produced but if things can always be improved and any advice would be great. thanks.
http://www.reefcentral.com/forums/showthread.php?s=&threadid=1130603
http://www.reefcentral.com/forums/showthread.php?s=&threadid=1130603
hahnmeister
In Memoriam
The 4" neck is a bit on the small side, but your neck is also taller. I think 5.5" is more what you might want, since dual Sedra 9000s should put you in the range of 2000lph of air if I remember correctly. This would prevent the larger bubbles from formig as well. Otherwise, your skimmer is an example of a taller, narrower neck working fine.
As for the microbubble problem, thats up to the throughput rate of the skimmer... slow it down if you are getting microbubbles.
As for the microbubble problem, thats up to the throughput rate of the skimmer... slow it down if you are getting microbubbles.
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