overskimming ha!!

[manderx]

. Swirling cannot have a net slowing of air and water inside the container with a constant input because the container has a finite volume

dude, you are trying way too hard to way overthink this. first, skimmers aren't sealed containers, the water level inside can rise and fall as needed/adjusted. and since the most air we can put into a skimmer (according to escobal) is 13%, we're dealing with small differences in total air volume, just a few percentage points.

 

[BeanAnimal]

I guess I should build on what manderx said as well with an example. This is in addition to my previous reply that assumed we were talking about a fixed amount of entrainment.

Take a bucket of water with a hose in the bottom. Set a bubble counter to push 1 bubble a second into the stagnant water. At any given time there will be only 1 bubble in the water.

Now put a strong swirl in the bucket (recirc pump with no air) and turn your bubble counter on. If the water velocity is strong enough it will pull bubbles with it. I hope you can see that though the bubble tries to rise straight up, it will be pulled along sideways slowing it's ascent because it is caught in the horizontal path of the water. If 1 second passes, the next bubble will be released, while the first is still entrained.

To add to the model, place 3 bubble dispensers in the bottom, that all fire 1 bubble at the same interval. 1 at the edge, one halfway between the edge and center, and the last in the center. In the stagnant water all 3 will rise at the same rate. Swirl the water hard and the center bubble will rise almos straight up due to it's position in the center of the swirling column. The next bubble out will take a longer path but may overcome the pull of the water. This of course depends on the velocity and the bubble buoyancy. The outer bubble will be more prone to getting pulled around in circles instead of rising.

Can you see now that in a fixed volume of water with a fixed input of air, that the entrained air volume can increase depending on the motion of the fluid?

 

[kimoyo]

<a href=showthread.php?s=&postid=7894668#post7894668 target=_blank>Originally posted</a> by BeanAnimal
the NET volume of air does not change (as you aleady noted). It is realesed, and the throughput of the skimmer does not change with regards to water either. Those are fixed inputs with dictated outputs.

Bean, thank you for accepting my invitation to this thread, finally we all can be at the same starting point. They wouldn't take my my word on this so now maybe they will accept yours.

<a href=showthread.php?s=&postid=7894668#post7894668 target=_blank>Originally posted</a> by BeanAnimal
However some coheared water/air molecules stay longer than others. It's that simple. For any given timeslice T there should be about the same amount of air and water in the skimmer. Some of that air could have been there for minutes, while some of it could have just entered and be on it's way out. The key is that not all of the air/bubble units will act this way. Some are independent of each other and follow shorter paths.

With a direct ascent, all of the air goes straight up and out. In a turbulant skimmer body this would not be the case, muc of the air would be sent on long journeys up and down before escaping.

The swirling is similar to the turbulance, but it is more ordered and less stressful for the tiny bubbles.

I've owned a barr becket and a deltec needlewheel. I've also seen a lot of other skimmers in action. Neither of those skimmers have bubbles going in a straight orderly "calm" ascent, just look at the skimmers. They've been turbulent with water going up and down and everywhere. The barr (and mrc) even has a mixing chamber before the water/air rises in the main chamber. After watching that aerofoamer video, to my eyes the swirling causes less turbulence that any of the skimmers I've owned, just watch the video. The air and water go straight thru piping and exit at an angle and then rises in a more orderly fashion. Again, we are comparing this swirling skimmer method to the other skimmer methods, we are not talking about a "calm" bucket of water with bubbles rising.

<a href=showthread.php?s=&postid=7894908#post7894908 target=_blank>Originally posted</a> by manderx
dude, you are trying way too hard to way overthink this. first, skimmers aren't sealed containers, the water level inside can rise and fall as needed/adjusted. and since the most air we can put into a skimmer (according to escobal) is 13%, we're dealing with small differences in total air volume, just a few percentage points.

I was hoping that Bean agreeing would have been enough. Firstly, becketts are pressurized so they are sealed with an input and output. All skimmers aren't sealed like becketts (with few inputs and outputs) but if we keep the in-rate and back pressure constant we can treat them as if there is a volume boundary at the top. For example, if you don't change the gate valve pressure or input gph on your skimmer, the water level should stay the same.

<a href=showthread.php?s=&postid=7895059#post7895059 target=_blank>Originally posted</a> by BeanAnimal
To add to the model, place 3 bubble dispensers in the bottom, that all fire 1 bubble at the same interval. 1 at the edge, one halfway between the edge and center, and the last in the center. In the stagnant water all 3 will rise at the same rate. Swirl the water hard and the center bubble will rise almos straight up due to it's position in the center of the swirling column. The next bubble out will take a longer path but may overcome the pull of the water. This of course depends on the velocity and the bubble buoyancy. The outer bubble will be more prone to getting pulled around in circles instead of rising.

You keep going over the same stuff. I agree, some bubbles will rise faster and at the same time other bubbles will rise slower (as with all skimmers, ie. your color example). Its the net we are talking about.

<a href=showthread.php?s=&postid=7895059#post7895059 target=_blank>Originally posted</a> by BeanAnimal
Now put a strong swirl in the bucket (recirc pump with no air) and turn your bubble counter on. If the water velocity is strong enough it will pull bubbles with it. I hope you can see that though the bubble tries to rise straight up, it will be pulled along sideways slowing it's ascent because it is caught in the horizontal path of the water. If 1 second passes, the next bubble will be released, while the first is still entrained.

Can you see now that in a fixed volume of water with a fixed input of air, that the entrained air volume can increase depending on the motion of the fluid?

Nope, you don't have a fixed output rate in this example like we have with these skimmers (which you agreed with).


Anyway, thanks so much for an interesting discussion. Later.

 

[BeanAnimal]

Thanks for inviting me... sorry I don't agree with your stance.

3 important points:

1) the NET volume is only one way to look at this in reality is not what the model is. It just make it simpler to talk about.

2) Of course it is a fixed output. 1 bubble per time T and a fixed volume of water. There is NOTHING variable. The model can be scalled very easily to fit the exact opertion of our skimmers.

3) We are in no way concerned with the NET dwell time or volume. We are concerned with the contact time between a single protien and a single host bubble.

We know that short contact times strip some protiens but not others. We want to increse contact time to strip other types of protiens NOT MORE PROTIENS. The NET amount of extraction does not incresae or decrease. (Unless of course there is a shortage of SHORT contact protiens and the contact times are not long enough to strip the long contact protiens).

As long as there is an abundance of all types of protiens, then the longer contact time will provide a better range of extraction. It is very simple.

So lets say that you have 100 air bubbles and each will remove a protien. You can either get 100 S protiens using a skimmer with short contact times. Or using a skimmer with longer contact times you can get a mixture of S and L protiens (a ratio) that still equals 100 net protiens removed.

 

[RichConley]

<a href=showthread.php?s=&postid=7895366#post7895366 target=_blank>Originally posted</a> by BeanAnimal
We know that short contact times strip some protiens but not others. We want to increse contact time to strip other types of protiens NOT MORE PROTIENS. The NET amount of extraction does not incresae or decrease. (Unless of course there is a shortage of SHORT contact protiens and the contact times are not long enough to strip the long contact protiens).

The issue I still see with this discussion is that right above. We dont know whats in our water, and we dont know absolutes for contact times.

Bean, I in principle agree with you here, but if its the case that these '2 minute' protiens aren't really present, and we only need say, 45 seconds max, we're optimizing away from whats actually optimal.

Thats the crux here, yes, a skimmer that has half its bubbles staying 10 seconds, and the other half staying 110 seconds is going to be ABLE to pull out more variety of stuff than a skimmer that has all its bubbles staying for 60 seconds, but only if the 110 second bubbles 1) arent getting stuck on short contact protiens, and 2) long contact protiens are a major percentage of the waste, and 3) 10 seconds is long enough to pull short contact bubbles.

If long contact protiens are scarce, say we add a skimmer that does 90% of its bubbles at 30 seconds, and 10% of its bubbles at 330 seconds. If 30 second bubbles are long enough to pull short contact protiens, then this skimmer will very quickly strip the short contact protiens, and the 330 second bubbles should eb able to get to the long contact protiens unmolested.

The above is probably confusing, but what I'm trying to say, is that I think that in any skimmer, we're going to have some turbulence, and thats going to cause a good amount of bubbles to stay around for a while, and a good amoutn to make an early exit, and I'm just not sure that we have enough information to say that optimizing towards one end is actually going to help.

 

[LBCBJ]

Just an observation...let's not get too stuck on proteins here, they are only a small fraction of the organics pulled out by skimming. An Organic Skimmer would have been a more fitting name.

 

[BeanAnimal]

Rich.. thats the beauty, we are not optimizing away really. If it sticks it stick. You could argue that the longer dwell after contact may cause release due to turbulance. However, the bubble is still dwelling and should recontact with another protien. It is really a WIN WIN having longer contact time.

The second problem is that we can not assume that longer contact protiens are scarce. We do know that we are not removing them if they exist. According to Escobal and many others they do exist. This is very common technology in the wastewater industry.

The bottom line is that we only know what the "experts" have said, and that is that contact time matters and the longer the better.

 

[LBCBJ]

<a href=showthread.php?s=&postid=7896027#post7896027 target=_blank>Originally posted</a> by BeanAnimal
If it sticks it stick. You could argue that the longer dwell after contact may cause release due to turbulance. However, the bubble is still dwelling and should recontact with another protien. It is really a WIN WIN having longer contact time.

I seriously doubt that simple water turblence would negatively affect molecular bonding. The only way those bonds could be broken would be by intense heat or possibly contact with certain other organic molecules

 

[BeanAnimal]

Beats the heck out of me... Like I said, I honestly can't find any drawbacks to long contact times.

 

[LBCBJ]

That's because there are none

 

[BeanAnimal]

I also think when kimoyo sees what he is not seeing.... he will go "wow how the heck did I miss that, it SO simple!".... been there done that plenty of times.

 

[LFS_worker]

water change today 21 gallons and cleaned both skimmers out ... all appears to be doing well ... finally figured out my microbubble problem ... I know that all the modifications are swaying the results even more but here are some more things I tried to "beef up the skimming"

1) I took the drain previous recirc mod and ran it to the mag24 for a recirc mod to the mag24. Works great ...

thanks for reading
Brian

 

[RichConley]

<a href=showthread.php?s=&postid=7896009#post7896009 target=_blank>Originally posted</a> by LBCBJ
Just an observation...let's not get too stuck on proteins here, they are only a small fraction of the organics pulled out by skimming. An Organic Skimmer would have been a more fitting name.

I completely agree, and I think a lot of people forget/overlook that.

I can pull whole PE mysis out of my tank with my skimmer. Thats got NOTHING to do with protiens, or contact time, or anything. Thats just something getting pushed to the top by the surface tension of bubbles. Theres no bonding going on there, its more physical than chemical.

 

[BeanAnimal]

I also agree... there is a lot more going on here than a simple dwell time or contact time. The great part is that there are a LOT of good skimmers out there, and a lot of good DIY projects out there.

Just a few years ago, the selection was horrible and limited to a few berlins and red seas or excalliburs. They cost as much as many of todays skimmers to boot.

Bean

 

[Gary Majchrzak]

<a href=showthread.php?s=&postid=7880992#post7880992 target=_blank>Originally posted</a> by kimoyo
Not really talking about nw vs. beckett, just what the 'swirling' does on your aerofoamer vs not 'swirling' on your aerofoamer. If you take that 45 elbow off the aerofoamer, I think the contact time is the same because the rate in/out stays the same, so the vertical component of the air/water mixture stays the same also.

Tangential injection of the water into the contact column can provide a swirling action that increases the contact time by slowing the upward migration of the air bubbles.
taken from The Reef Aquarium vol. I by Delbeek/Sprung

have you done the 'airstone in a bucket of swirling water' thingy yet, Paul?

<a href=showthread.php?s=&postid=7878554#post7878554 target=_blank>Originally posted</a> by RichConley
Gary, a while back someone did some tests on aquarium water using DI water (or ozonized salt, something very clean basically) and some aquarium water that was visibly yellowed, and found that at typical aquarium depths, there was little to no difference in lighting intensity. The real difference comes in the fact that the corals NEED less light in a lower nutrient environment.
I'm gonna try to find the tests.

any results yet, Rich?

<a href=showthread.php?s=&postid=7902660#post7902660 target=_blank>Originally posted</a> by BeanAnimal
... there is a lot more going on here than a simple dwell time or contact time.

There definitely is... and it's called processing power.
Beckett driven skimmers (like the Aerofoamer) use a powerful pump to increase the air-water flowthrough (in/out) rate.

 

[tuberider]

<a href=showthread.php?s=&postid=7902581#post7902581 target=_blank>Originally posted</a> by RichConley
I completely agree, and I think a lot of people forget/overlook that.

I can pull whole PE mysis out of my tank with my skimmer. Thats got NOTHING to do with protiens, or contact time, or anything. Thats just something getting pushed to the top by the surface tension of bubbles. Theres no bonding going on there, its more physical than chemical.

A quote from Stephan Spotte "Many surface active fractions of the DOC can be concentrated and removed in foam produced by foam fractionation. This process is also called air stripping and protein skimming; the latter is inaccurate in implying that only proteinaceous substances are removed."

I think he kinda knows what he's talking about.

 

[swimboy123]

This thread will amaze any reader if they start from the beginning and see how incredibly off topic it can get.

 

[Gary Majchrzak]

<a href=showthread.php?s=&postid=7904561#post7904561 target=_blank>Originally posted</a> by swimboy123
This thread will amaze any reader if they start from the beginning and see how incredibly off topic it can get.

It sure is a popular thread. It's one that actually contains some interesting posts, too- way better than just another "ID this Acro" thread.
We're not totally off topic, either. Accelerating the export of DOC's with good protein skimming allows the reefkeeper more control of the reef aquarium environment- and that is a very good thing.

 

[BeanAnimal]

Even better the conversation has stayed fairly calm and cordial with very few ruffled feathers or hurt feelings. It's been a great thread!

 

[Angel*Fish]

<a href=showthread.php?s=&postid=7904713#post7904713 target=_blank>Originally posted</a> by BeanAnimal
Even better the conversation has stayed fairly calm and cordial with very few ruffled feathers or hurt feelings. It's been a great thread!

I was just going to post the same thing! I've been following it from early on - great discussion guys! And in my opinion this bubble discussion is very on topic to the main point of the thread.