5' Skimmer Build in Progress

Well the water level in my tank is about 59 inches. So I figure the total skimmer height will be about 60 inches from bottom to top of cup. The will prevent disaster. The water level in the overlow is about 56" so this would be my max water level (overflow fed skimmer). The current plumbing will allow the water input to be at about 41" up the side of the skimmer. Of course the hartford loop will dictate the true height someplace above that.

So I figure the water level will be about 45"-50", this will still allow a decent flow from the overlfow box. The stones will be about 10" off the bottom. I will be using a cleanout T for access.

I figure a bubble rise height of about 40 inches or so to the top of the water... another 10 or more to the top of the neck.

I did not plan on recirc... but will put the iniseals in in case.

Bean
 
Uniseals can be added after the fact.

On a 4" skimmer you will have to keep the flow <3 gpm if you want to avoid turbulence.

The 4" skimmer will give you .9 minutes of water dwell and 42 seconds of dwell for micro bubbles. The larger bubbles will only last 5 seconds.
 
I see your trying to talk me into the 6" skimmer... but that means I gotta have a bigger air pump, and will not be able to easily adapt an acrylic skimmer neck on :(
 
No influence at all, just statistics.

There is a 6" X 4" rubber cone on my skimmer. From that point you are back to your 4" design.

The 6" unit will not change your airdwell significantly if you use recirc. It will change water dwell though.

Water dwell would be over 2 minutes. Air dwell would be 37 seconds with 2 gpm feed and 2gpm recirc.

The 4" would yield better air time without going turbulent and without a recirc, but water dwell suffers.
 
I was going to avoid the ferncos in hopes of a more gradual skimmer neck. I sent spazz an email to see what he would charge for a flange cone and neck. I don't have the time to build my own, unless I do it out of fiberglass and use a funnel or something as a form. This still leaves me having to design a watertight flange or find a 4" union.

Bean
 
One point is that the size of the bubble at detachment from the pore has as much to do with the surface energy differences between the solid and liquid as it does the pore size. How's that for a run-on? I wonder if depositing a thin film of some other higher surface energy material on the surface of the silica would help. Also, there is a point where flow rate determines the bubble size. It would be best to keep the flow rate below this value.... just thinking...

So 1.67 in./s was the smaller ones... and the larger ones too fast? What do you think the effect of adding more stones would be, that is, if 'stone' could cover most of the entire cross-sectional area on the bottom? So, what are you hoping to accomplish by increasing the air flow? Is this to get your 13% or does it have something to do with bubble size?

By the way, Escobal didn't reference the 13% number... I also feel that the 2x per day turnover is not necessarily the appropriate number. He did a proper job of getting from the 99.99 etc to 2x per day, but the 2x came out of nowhere...

Bubbles are less likely to coalesce if they have already adsorbed whatever surface-active solutes are present. The theoretical maximum packing for spheres is 74% volume. As such, it might make sense to taper skimmers so the bubbles at the top are more concentrated. This would allow more stones in the bottom, with more bubble-producing pore sites, and less flow per site. Seems tricking to build, though... what do you think?

Another point... I think it would be very hard to ascertain if a bubble is saturated (with whatever it is we want them to be saturated with) by the time it reaches the foaming portion of the skimmer. Thus, it would be hard to guess that some particular dwell time was best. More can't hurt though, right?

I haven't looked at the spreadsheet calculator yet, but that's a very useful contribution. I don't think we should kill this air pump skimmer idea just yet... it would be really great to get venturi performance at 1/10 the watts... looking forward to updates and feedback, etc.

G1
 
By the way, I'm trying my best to think of a way to make this work, as I'm about to DIY a bunch of tank stuff. Also, those sweetwater pumps really are quiet. I have both the SL14 and 24. Haven't done any skimmer testing with them though. They're for freshwater...

G1
 
I am not convinced of the 13% number either. Is it 13% water to air in regards to the standing water height? 13% of the total skimmer volume?

If you keep lowering the hartford loop and adding more air, then the air/water ratio will rise. At some point there will not be enough water to allow the foam to rise up and reach the neck efficiently OR the air will cause large burps and bubbles instead of a smooth steady rise. If it were me I would test the theory to it's extreme by lowering the loop and turing up the air until I found that point.

Bean
 
not to change the subject... but isn't that Kepler's Conjecture?

I think 74% is achieved using a hexagonal lattice. Question is do sheres randonly or naturally compress or fall into this space? I think i read somewhere that at best a box of equal size spheres would be randomly distributed and take up 64% or something.

Bean

Bean
 
I also had an idea that the loop could be more easily adjustible using flex tubing... just support it at different heights to lower/raise the level in the skimmer...

G1
 
I am going to give the expanding repair couplings a try. They have 2 o-rings in them and telescope. Each one give about 5" of movement. The other idea (if space is not at a premium. Would be to use an elbows and unions to form a loop similar to a brace and bit type of handle laying on it's side. Think of a teakettle or 5 gal pail. Losen the unions and allow the "handle" to rotate up or down to adjust the height. This would give you the radius of the "arms" as the adjustment range.

However... I think a few extra pieces of pipe and some ferncos will be idea to get it dialed in close. They can then be replaced with rigid pipe and compression couplers or the telescoping repair fitting. This should allow enough to keep the skimmr tuned from day to day.
 
I also had an idea that the loop could be more easily adjustible using flex tubing... just support it at different heights to lower/raise the level in the skimmer...

G1
 
I don't know about Kepler, but yes, 74% is for stacking of close-packed planes. It's the same for a hexagonal close-packed or face-centered cubic structure.

Bean, is the expanding repair coupling for the level adjustment? See my last post.....

G1
 
I was thinking of flex pvc type tubing... that's sort of hard plumbed. I wonder what the super fine diffusers do at a lower psi than 25. Not emit at all? Maybe they made a mistake and it's 25'' not psi...
G1
 
tinygiants:

as for bubble size, could you be pushing too much air through the stones? I seem to remember that we want to under power the stones. I sent an email to AES describing a skimmer like yours and asked for their advice. Here is part of their reply:

I will give you a general sizing guide you can use. Since your pipe is only 6" you can use 2 air diffusers, vertical if you please, and I would say 2" diffusers should be fine. ....

Given that comment, and your results so far, I am thinking that 3 - 4 2" stones mounted vertically might give a lower big-bubble output.
 
<a href=showthread.php?s=&postid=6435060#post6435060 target=_blank>Originally posted</a> by BeanAnimal
I am not convinced of the 13% number either. Is it 13% water to air in regards to the standing water height? 13% of the total skimmer volume?

If you keep lowering the hartford loop and adding more air, then the air/water ratio will rise. At some point there will not be enough water to allow the foam to rise up and reach the neck efficiently OR the air will cause large burps and bubbles instead of a smooth steady rise. If it were me I would test the theory to it's extreme by lowering the loop and turing up the air until I found that point.

Bean
Click to expand...
True.

If I lower the loop, do not change flow rate of water and of the air, then the ratio will stay constant. Only the height of the water air solution will change, thus effecting my ability to have wet or dry foam.

13% was refferenced by Escobal. At least inb the online refferences I have found. I copied and pasted the article in the skimming 101 thread.

Dale
 
I do not believe that I have to much air to my stones. I got those type bubbles even with the air just seeping out.

I will play with my stones verticle to see if it makes a difference. As it is now, I have 3" X 3" square of stone (not counting the air line elbow) inside the 5.75 circle. I am touching the circle perimeter at the corners.

Dale
 
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