Skimming conversation

[dnjan]

Seriously, though, I don't really think the zeta potential would have much of an effect. That interesting little document on zeta potential (thanks for posting it, by the way) includes a graph on page 4, of zeta potential versus electrolyte concentration. The units for electrolyte concentration is mg/l, which I believe is approximately the same as ppm, correct? For the monovalent cation system shown (KCl), the zeta potential approaches zero at a concentration a bit above 20,000 mg/l (20,000 ppm, or 20 ppt). Assuming that another monovalent cation system (NaCl) would have a similar zeta potential versus concentration behavior, and the fact that the water we are trying to skim has an NaCl concentration above 30,000 ppm (30 ppt), it looks like the zeta potential would be close to zero.

Please feel free to correct the above if I made a major error - the cold medicine I am taking may have impaired more than just my ability to operate heavy machinery.

I would assume that differences between plastic and titanium needle-wheel rotors may have more to do with surface texture of the rotor, and the laminar-turbulent interface, than zeta potential differences due to different rotor materials.

 

[mojoreef]

The titanium needle-wheels were put in as a fix for the ceramic ones that kept breaking. Needle wheels are heavy and if not perfectly balanced they can wobble and through everything out of wack.


Mike

 

[ldrhawke]

I think everyone is missing the point of my discussion. It is simply that particles in a fluid often develop a charge. This charge does effect how they are attracted to each other or the bubble in a skimmer.

In the case of a colloid with it's like charge particles keeping the particles in suspension or a particle charge from energy input into the fluid from pressure, velocity, or temperature change in a fluid. These charges can have an effect on how rapid and strong a bond they make to fine bubbles, which can directly effect the performance of a fine bubble skimmer.

A pinwheel impellor doesn't neccessarily perform or follow the same rules the same as a fine bubble air stone skimmer. The pinwheel impellor is causing a higher energy impact on the fluid, which different then the often recommended almost laminar flows in an airstone skimmer. It is possible that like running a plastic object thru fur or hair that there is an electron transfer of of energy when both in a different way.

I am not even saying a titanium metal impellor cause more energy transfer , but I have yet to see or hear any sound argument that it could not be taking place. And it is logical to assume there is a transfer of energy any time you have a steep gradient from changes in pressure, velocity, or temperature in fluid flow. I would assume a nylon or plastic impellor might even be more effective, based on what we can easily show by running a nylon comb through your hair and picking up a piece of paper with it.

Again does this have a significant affect on a skimmer? Base on the bubble particle attraction principle a skimmer works on, it is a good assumption it may well.

It is the type of testing a smart skimmer mfg. should be doing, but the fact is most if not all of them are simply small plastic fabricators and not scientists. They are more concern that a skimmer makes a lot of bubbles and removes organic waste, not how or why it does. The Bubble King mfg seems to feel a titanium pin wheel makes better bubbles, from what I have seen they have done better testing than most skimmer mfgs so I don't totally discount it. Although I suspect it is a little more marketing hype than fact.

Again my point is simply that any rapid energy change, whether from velocity, pressure, friction or temperature in a fluid, does affect a particles energy in that fluid and I suspect also the performance of a skimmer.

 

[mojoreef]

ldrhawke I know where you are coming from on this, but I dot know if it is enough to really make a reaction take place. Plus the wouldnt you assume that the medium (water) would absorb it??

Mike

 

[dnjan]

slight change of subject

What I am most interested in is the range of organic materials that can be removed by specific skimmers (for whatever reasons). LRDHawke (or anybody else, for that matter) - do you have access to equipment to determine the chemical type and hydrocarbon length of the organics in the skimmate?

I suggested earlier, and would really like to see which skimmer removes the broadest range of organic materials. If I have to wait for organics to be naturally oxidized into the most skimmable form(s), that is a problem. If, however, a skimmer removes a broad range of organics (even if slightly more slowly in terms of total mass of organics removed), that is better in my book.

This is a good opportunity for somebody with lab access to step up.

 

[ldrhawke]

ldrhawke I know where you are coming from on this, but I dot know if it is enough to really make a reaction take place. Plus the wouldnt you assume that the medium (water) would absorb it??

Mike

We are talking particle and bubble charge which is the whole basis of what makes a skimmer work. It is the power that attracts and hold onto the tiniest particles of waste in suspension onto the bubble which lifts it so it can be exported. If the bubble and particle are given the time to dissipate the charge then water does absorb it. If it doesn't absorb it it remains a colloid suspension.

 

[RedEyeReef]

Why can't we use the Four Point Ultra Fine diffussers? Is it because air particals through normal filter is not enough to keep them from getting clogged or are they made out of metal? Wouldn't they give us smaller bulbs?

http://www.aquaticeco.com/index.cfm/fuseaction/product.detail/iid/9775/cid/2339

 

[mojoreef]

They push out about the same bubble size Redeye. The biggest set back is that they have an operating range of between 25 and 50 psi.


MIke

 

[Maxx]

At what range do the others operate at?

Nick

 

[mojoreef]

2 to 5 psi. Basically those unit are used with oxygen tanks or blowers...maybe the odd compressor.


Mike

 

[rufio173]

They push out about the same bubble size Redeye. The biggest set back is that they have an operating range of between 25 and 50 psi.


MIke

The same bubble size? I don't know about that Mike... there's a reason you would need 25 to 50 PSI to blow air through those things.

Peace,
John H.

 

[mojoreef]

yea the bubbles are a bit smaller but I think it has more to do with the manufacturing (ex: resin bonded)


Mike

 

[RedEyeReef]

2 to 5 psi. Basically those unit are used with oxygen tanks or blowers...maybe the odd compressor.


Mike

I'm glad to hear our stones has about 2-5 psi, that will tame down my SL 56 for my skimmer.

 

[rufio173]

The stones that we are using will be around .5 PSI to .75 PSI

Peace,
John H.

 

[mojoreef]

Damm John I cant believe I am so brain dead on these numbers, rofl. I dont even know where I got those from. I refer all technical air stone skimmer questions to Rufio from here on in......man


Mike

 

[rufio173]

That's allright Mike... that's what we're all here for, to help each other out. I know I've had my share of brain farts in the past.

Peace,
John

 

[mojoreef]

Ahh i was quoting the pump psi numbers, man must be an age thing.


Mike

 

[rufio173]

Being forgetful has its advantages. I'm sorry Honey... was I supposed to clean out the garage this weekend? Hehe

 

[RedEyeReef]

The stones that we are using will be around .5 PSI to .75 PSI

Peace,
John H.

Darn, good thing I build an extra valve in my manifold to bleed off the extra air.

 

[rufio173]

Redeye,

Take some pics when you've got the thing up and running

Peace,
John