Questions About Building a CC Skimmer

[LiquidShaneo]

I am contemplating building my own 4' airstone driven counter current skimmer and am wondering if anyone has done this and if so what their results were. I am using the following book to guide me in the proper design of the skimmer for my tank:

Aquatic Systems Engineering: Devices and How They Fuction by P.R. Escobal

And I am using Larry Jackson's PVC component listings that he used for his DIY skimmer (plans available from http://www.ozreef.org/). Has anybody else used this book to DIY a skimmer for their tank and if so, how accurate was the engineering principles behind it? I'd like to hear other peoples' experiences. I basically have all the equipment to run this skimmer. I just need to build the skimmer body.

Thanks in advance,

liquid

 

[LiquidShaneo]

^

 

[Aaron Shelley]

I have built about 10 or 11 skimmers over the last 9 years. The first ones were as you plan to build. I prefer the venturi ones as they are more productive and require less maintenance size being equal.

 

[LiquidShaneo]

Anyone else?

 

[KW]

I have read that book and I chose to use 6" PVC to build my skimmer.

I will disagree with Aaron and say that I like airpump skimmers better than venturi. There, now are you thouroughly confused?

The only type of skimmer that I would consider replacing my skimmer with is an aspirating skimmer, i.e. Euroreef.

If you need some Luft pumps I have a wooden box with four of them inside of it. I'd let'em go real cheap

 

[Endoplasmic]

I'm a newbie sorry... what's a luft pump... and if you meant lift pump.. .what do those do and how do they function?

 

[Snailman]

I am a CC skimmer fan also. They are the only design where you can adjust the air water ratio and that are also more plankton friendly that the other designs. Ron of Ron's Saltwater Heaven makes CC skimmers and he puts a regular PVC pipe cap on the bottom. His reasoning is so that stuff does not collect down at the bottom and he is right it doesn't. I think that Ian McDonald has a better design and I can email you a copy of it if you want it. The air you can pump into a CC skimmer with out it flooding is limited by the reaction tube diameter. Ron uses a 2" tube and Ian uses a 3 1/2" tube. I have built one of Ian's top ends for my Ron's skimmer and I am going to put it on this weekend. It should make the skimnmer really kick rear end.

 

[Flatlander]

Right on about the neck size, Snailman.
I finally gave up on the one I was trying. Gave it to my lfs to use on his downstairs sumps. What a waste of $200
Were building a larger model, such as you guys are trying. For sure the returns will be two- one inch pipes, so it can handle some flow.
We are also making a larger collection throat, an adjustable size neck piece and a large collection cup. It will take a feed from an Iwaki 20 pressure pump and use a pair of 6in. airstones.
Since our posts on this before, we have found that the smaller airstones do not make a fine enough bubble from big airpumps. There was no way not to overdrive the skimmer. The new one will correct all of this, we hope.
Also tried a 5ft. venturi with a large return system. Tried to drive 2 airstones in it and again the same problem of overdriving the skimmer with a large & very turbulent action in the neck. Again to rough for a good skimmate.

 

[Snailman]

Doug... two 1/2" pipes should be plenty big enough to carry the return water in a CC skimmer. The aim is more air not more water so the air/water ratio goes up to improve the efficency.

 

[Flatlander]

But,but, , the problem I have now is that as good as my Euroreef is, I do not pass enough of the tanks water.
The reason for the bigger returns was to allow the use of a bigger pump and still allow the room to crank up the stones which I could not do in the smaller skimmer. No!

 

[Snailman]

I'm a newbie sorry... what's a luft pump... and if you meant lift pump.. .what do those do and how do they function?

We mean Luft. It is a model of Tetra air pump. You will see it refered to as the Tetra Luft or just The Luft. It is a high pressure pump that can drive large air stones under 7' of water so they are popular with CC skimmer owners.

 

[Snailman]

Doug... The one tank per hour for a skimmer is pure bunk. What you want a skimmer to do is remove the gunk from your water. The higher the air/water ratio is the better the skimmer works up to a ratio of 16/1 where it's efficency levels off. You can only pump so much air into a wooden airstone and still keep a small bubble size so if you increast the water flow you are making the skimmer less efficent not more. If you can get a hold of the 1999 annual USA Marine Fish and Reef there is a wonderful article that explains this much better than I have. I run my Ron's skimmers at a very low water rate and drive the air stones with a Medo ACO902 air pump.

 

[LiquidShaneo]

I agree with Snailman on this: "The one tank per hour for a skimmer is pure bunk." This is a pretty common misconception from what I've seen... Doug, the faster you run water thru your skimmer the *less efficient* your skimmer becomes. You need to maximize the amount of air that hits each water "glob" to maximize waste export...*not* the other way around. An air bubble can only hold so much waste so you want to pass as much air past dirty water as possible to remove as much of the krud as possible per unit volume. Pump up the air and turn down the water flow...

liquid

 

[YZ]

Shane I was thinking about making my own skimmer also but decided to stick with what I got since I'm not getting a bigger tank yet. But use extruded tubing for the skimmer body. Not the pvc that you can't see into. With the extruded just use a 6" cap on both ends and glue it with weld-on #16, this stuff is cheap enough to use for a pro look.

 

[Snailman]

I am a fan of PVC skimmers so they stay clean inside but if you decide to build one out of acrylic I wiil be glad to give you some help on the flanges. Also http://www.usplastic.com is a good place to get acrylic sheet and tube as welll as all kinds of cool stuff for your DIY projects and they are super to deal with.

 

[pacmans]

Hello everyone interesting thread

Doug I have to agree also with snailman on this que. of the ratio of (water flow vs air)
In water tretment plants through out the US and Canada and other parts of the world they use foam frictionation or skimming in the purifying of water pollution in tretment plants and have for some time.
The motors that drives the air blowers are big say 150 to 200 hp, the blower is about 5' across and about 6' high and I can say vary noisy the air then is blown into a water contact channel and comes in contact with the slow moving water to allow more air contact time with the effluent there are also millions of good guy bugs in the chamber that also break down the effluent but that is a microbiology
thread and a little off topic here.

(just a wierd kind of fact for any one reading this)

If you were to fall accidently into the channel you would sink like a rock because the buoyancy of the water has been take out by the ammount of air being pumped in and the slow movement of water.
I guess the rate of water passing through the skimmer would depend on what you set the pump output at via a valve.


Just wondering though with cc skimmers don't you find you have to tweek them alot to get the air just right?
and is the ratio 16/1 is that 16 cubic/ft of air to one gallon of water?

pacmans

 

[Flatlander]

So are we saying that a skimmer with an injection system or downdraft and runs on a large pump, with large volumes of water is not as efficient? I thought it was the large amount of water passed through them that makes them so efficient at skimming large tanks?
My cc did work better with less water flow and more air but IMO, was not processing much water at that rate.
Does not a larger chambered Euroreef with 2 or 3 pumps, put more water through it, thus allowing it to skim larger tanks than my single pump model?

 

[pacmans]

Hi doug
I am not sure about how much water should go through the skimmer.
I was always under the same impression as you were until rescently a hi ratio of water to air is what all the lfs tell us reef hobby nuts.
The more water through the skimmer meant more skimming the tank of waste.

Newbee QUES here

But I have always wondered if there was a good rule of thumb for this ratio that is why I found this thread interesting to see if some one out there new what is an ideal turn over rate for a tank of any given size?


But I am also curious do you have to adjust the CC skimmers more often to dial them in but once they are set do you have to play with them alot or is it locked in until your air stone needs replacing and how often would that be

I am interested in a CC skimmer for a future tank just like to do the research first you know ask ask ask, to get a better understanding of this relationship and what is the advantage to CC this may also help liquid shaneo on the correct size to build.
Not trying to start a flame here of venturi over CC everyone has there preference just like to know more about CC

anyone

Thanks
pacmans

 

[Snailman]

Doug... The problem with a venturi or pin wheel skimmer is they take a lot of water to begin with to even work. To increase the air flow you have to increase the water flow so the ratio does not change. This is why industrial scale foam fractioners are air based just like pacmans said. It is far better to pass 1/4 tank volume through your skimmer an hour and have it be real clean when it came out rather than moving dirtier water out faster. If you can find a copy of 1975 Sep Sci 10(6):673-688 there is an article that explains how this ratio was determined. It was written by S. I. Amad. Also there is a Weeks and Timmons 1992 article on the feasibility of using foam fractionation for the removal of disolved and suspended solids from fish culture water in Aquaculture Eng 11:251-265.


pacmans...The ratio is cubic feet of air to cubic feet of water or any other measure as long as both the air and the water are in the same measurement. One cubic foot of water is 7.5 gallons.

[Edited by Snailman on 12-22-2000 at 09:04 PM]

 

[LiquidShaneo]

I again totally agree w/ Snailman. Grab yourself a copy of the two articles that Snailman mentioned and also grab yourself a copy of Aquatic Systems Engineering: Devices and How They Fuction by P.R. Escobal (which you probably can get thru interlibrary loan). They will explain *everything* about efficiency, etc. along w/ equations and all if you really like to get into that kind of stuff (which I do!).

In case you're interested in reading about a comparison of the EuroReef skimmers with other high powered skimmers, please refer to:

http://www.animalnetwork.com/fish2/aqfm/1998/nov/product/default.asp

Later!

liquid