How does it work? Vol 3: Closed loop

[jango]

This form of a loop is less hydraulically efficient but has other benefits

Matt, what benefit's?

(not being a smart a** honest question)

 

[NateHanson]

A Calfo loop certainly can be a closed loop, right, if the framework of outlets above the tank are supplied by a pump drawing from the display tank, right?

I'd say one disadvantage is reduced light penetration if the surface has lots of turbulence.

 

[Matt L.]

Speaking of being a smartarse

Matt, what benefit's?

1. I don't know, you've gotta ask Calfo, and
2. What is your avatar a picture of?

Seriously, I believe the benefit is that there is water jetting against the surface to cause perhaps increased oxygenation? I honestly don't know. I just heard someone say some time that this form of a closed loop has advantages, but that's it. Personally, I wouldn't want the pipes above my tank and the sound of the water jetting,

Matt

 

[Matt L.]

A Calfo loop certainly can be a closed loop, right, if the framework of outlets above the tank are supplied by a pump drawing from the display tank, right?

A Calfo closed loop certainly is a closed loop by a reefing definition. Most people should just stop reading here

However, none of our loops are technically closed because the tank is open to the atmosphere (there is headspace). If you were to take a tank, and seal the top so that there was no air in it, then the reefing closed loop would also be a closed loop under the hydraulic definition.

Matt

 

[jango]

A Calfo closed loop certainly is a closed loop by a reefing definition.

Not if it were set up as first described then it would be a return. IMO extra oxygenation would not be needed if you have an overflow and a skimmer. It would just create a less permeable surface for light to penetrate. I would think it would be perfect for a tank with no overflow and sump.

Matt, my avatar is something that very few would recognize at a glance..

 

[dedfish]

Could someone explain what a calfo closed loop is? How about pictures? I've heard the term before but I'm not sure if I know exactly what it is.

Hmm...I think I know what Jango's avatar is, but I could be WAY OFF...but maybe being WAY OFF makes me right on. Hmmm...I wonder if I'm right.

 

[JohnK]

Matt,
I actually put that in quotations hoping that you would elaborate
(I know your always good for those explanations that make my head spin, but are correct beyond our reefing terms). Thanks


Greg,
Is that a closed loop by reefing terms? I may have been unclear but the diagram I was referring to before seemed to show a return pump from the sump running up to a manifold above the tank. Wouldn't this really just be a creative return and not a "closed loop" as the term is commonly used? I'll try to find the diagram I was talking about and post it, that might be better than my confusing way of wording things. Thanks

Also, will increasing surface turbulance decrease light penetration or will it just change the light distribution a bit?

 

[Chris A.]

I think on the Calfo closed loop the pump is in the main tank and not in the sump.(I think)

 

[JohnK]

Here's the link to the diagram I was talking about.

http://www.wetwebmedia.com/SystemPIX/Image6.gif


Is this a correct drawing of a "Calfo Loop"? I would think that it is only a "closed loop" in the common use of the term if, as TOOMANYFISH just said, the pump is located in the display (and the outputs are submerged). Even then there would be a bit of head pressure since the return points are above the intake point (it sure is easy to make something simple start to get complicated when a bunch of reefers begin to discuss it).

jk

 

[JohnK]

"Even then there would be a bit of head pressure since the return points are above the intake point"

This is actually incorrect isn't it?
if you pump water from one point in a container up to a higher point in the same container, but the outlet is still submerged, will there be any effective head pressure (beyond any head from elbows or friction in linear pipe)?
Matt......

 

[Matt L.]

I forgot I was Δ-enabled.

Here's the link to the diagram I was talking about.

http://www.wetwebmedia.com/SystemPIX/Image6.gif

That's not a (reefing) closed loop -- its just a creative return.

Perhaps Calfo means "loop" by referring to the ring shaped pipe manifold. He should just call it a "Calfo Ring" then.

And by the way, if the ring manifold is symmetric as he has drawn, it need not even form a ring (it would be hydraulically unnecessary because the flow between the farthest two points from the source of input into the manifold would be zero, i.e., a dead spot).

Even then there would be a bit of head pressure since the return points are above the intake point (it sure is easy to make something simple start to get complicated when a bunch of reefers begin to discuss it).

If the Calfo Ring were used as the discharge for a reefing closed loop, then yes, there would be additional head on the pump due to the fact that discharge ports are located above water while the intake is located at the water surface.


For all as well,

You may think of the total head a pump has to deliver as being the difference in elevation head plus the head losses in the system.

hTOT = Δz + hL

where: hTOT = the total head the pump must deliver, Δz = the difference in elevation head, and hL = total head losses.

But for a reefing closed loop, Δz is zero!!!

Why? Δz is the difference in elevation between the water surface of a body of water that a pump draws from and the water surface elevation of the body pump discharges to. Because for a reefing closed loop, the pump draws from the tank, and discharges back to the tank, the water surface elevations are the same and difference in elevation head is zero!

Note that the elevation of the pump doesn't factor in to this equation.

Matt

 

[dedfish]

That to me is not a closed loop since the pump is located in the sump. If you pumped water directly from the tank to the plumbing arround the top of the tank I might consider it closed.

 

[Matt L.]

if you pump water from one point in a container up to a higher point in the same container, but the outlet is still submerged, will there be any effective head pressure (beyond any head from elbows or friction in linear pipe)?
Matt......

Yes.

The only pressure will be due to frictional losses because in the equation:

hTOT = Δz + hL

Δz = 0, so hTOT = hL

the key point is that you are pumping within the same container, or that the water surface of the suction water body is the same as the water surface of the discharge water body.

Matt

 

[Chuck Spyropulos]

Benefits of the Calfo loop include increased oxygenation and more importantly allows a more random water flow than a single return.
You would be moving the same volune of water but the velocity out of each Tee'd nozzle in the loop would be less....so you could get high volume, low velocity flow with the right design. Also, you do not need to drill holes in your tank to plumb the return. You only need holes for the drains.

 

[JohnK]

Matt, thanks

you pretty much said exactly what I was thinking but explianed it more clearly.

Is this a correct drawing of a "calfo loop"?

(just looking to add to the informational thread)

jk

 

[Matt L.]

Jim,

I'm sorry, but I don't see anything in your post. Is there supposed to be an image?

Matt

 

[Matt L.]

Benefits of the Calfo loop include increased oxygenation...

I agree. You cannot get such oxygenation with a traditional closed loop design...

...and more importantly allows a more random water flow than a single return.

Yes, more returns always increases the randomness of flow with the number of returns. However, you will get about the same degree of randomness with multiple returns on a traditional closed loop.

More importantly, I argue that if randomness of flow is what you are going for, you should stick with the multiple discharge traditional closed loop and add a randomizing device (SCWD, Oceans Motion), as I don't see how you could easily modify the Calfo closed loop to incorporate one (you would have to start by making it not a ring!)

Matt

 

[jango]

You cannot get such oxygenation with a traditional closed loop design...

Oxygenation has nothing to do with a closed loop.
That is what your overflow and skimmer do. It is about moving water.

 

[JohnK]

Matt,

check the link on post #89 half way up this page.

 

[jango]

Is this a correct drawing of a "calfo loop"?

That would be the picture directly from his article in advanced aquarist's.