Help me further understand skimmer ratings

[snowmansnow]

OK so explain
air draw for me?

Is it just a measurement of air movement thats the pump can pull to make bubbles, or is there more to it than that?

I've seen LP/h AND CFH (or CFsomething).

What are the differences?

Also, how does skimmer size (as far as the body tube) dictate what the most effective air pull for the given pump should be?

IN other words, I've seen that a massive super bubble making pump will top out before it reaches its potential unless it is paired with the appropriate body size.

Thanks for any help you can offer.

B

 

[purplegorilla]

Lp/H Liter per Hour (metric)
CF/H Cubic Feet per Hour (standard).

The more air the pump draws in, the more bubbles it produces. The more bubble it produces, the more surface area it makes. The more surface area it has, the more proteins it skims.

So, as technology improves. You will eventually get<u> smaller pump</u> making more bubbles comparing to <u>bigger pump</u></em> that draws more amps producing less bubbles.

 

[jmaneyapanda]

ares;449748 wrote: purple has it right, and thats about where the extent of the science ends.

there is also the size of the bubbles, smaller bubbles have more surface area for a given volume of air than would larger bubbles, so presuming the air intake is the same for 1 setups, the only way to seperate the 2 would be to have 1 chop the bubbles up smaller.

as for body size, theres no rules here, generally larger is better, how large does it need to handle this much air? who knows. but larger does mean hopefully you can have less turbulence(turbulence is bad, causes protiens to get sheered off the bubbles) and more flow(all of our bubble making methods are byproducts of flow, plus the actual circulation of water through the body). taller bodies also allow for longer contact time by making the bubbles rise longer.

Right, so in essence, air draw means nothing unless you look at the engineering of the entire skimmer. IMHO, air draw has just become something for manufacturers to use to sell their product (marketing ploys).

 

[jmaneyapanda]

ares;449771 wrote: well its important... I mean, it is the bottom line realy, but strapping 6 needlewheels to a dixie cup wont work out real well either. same as putting a venturi on a rio pump and mounting it to a trash can sized body wont work out. there is some happy medium, but the details are more art than science.

The question is will 6 needlewheel skim more that 5 on a given skimmer? Skimmer companies want you to believe YES. And thats why they gush over how much air the pumps draw. But, in practical realities, this isnt always true at all. For example, a very ell know skimmer company found that pushing more air into a skimmer actually decreased its productivity at a point, so in this case more air was worse.

 

[ichthyoid]

If I remember correctly, P. R. Escobar ( Aquatic Systems Engineering: Devices and How They Function ) calculated the optimum air to water ratio to be 13% for greatest skimmer efficiency.

 

[snowmansnow]

ichthyoid;449827 wrote: If I remember correctly, P. R. Escobar ( Aquatic Systems Engineering: Devices and How They Function ) calculated the optimum air to water ratio to be 13% for greatest skimmer efficiency.

Water being how much h2o the body holds?

 

[ichthyoid]

SnowManSnow;449856 wrote: Water being how much h2o the body holds?

Yes

 

[jmaneyapanda]

How does this "magic number" come into play with flow through on recirculating skimmers? Escobar work is over 10 years old, if im not mistaken, and skimmers ahve evolved since then.

 

[ichthyoid]

As I recall, Escobal calculated this based on an optimal fluid density. This would be independent of bubble size, etc.

It appears obvious that a higher surface to volume ratio (more well distributed air), would work better. Modifactions using mesh to chop the bubbles finer tend to confirm this, though I have not seen any data to that effect.

(I don't possess the book, but would LOVE to have a copy),

 

[ichthyoid]

I found the article I was referring to... here is a quote:

According to Escobal: "...the volume of air in a skimmer can never be greater than about 13% of the volume of the skimmer or the bubbles will merge. Experimental measurements are in agreement..." (Escobal, p. 96). So if you hear any manufacturers out there claiming that their product will inject more than 13% air into the skimmer body, then I would highly suspect that they're not going to be able to acheive the proper bubble size inside their skimmer.

Below is a link to the article: