DIY CC gravity fed skimmer

[Worldwithin]

I am looking to build a counter current gravity fed skimmer, similar to a Red Sea Berlin style skimmer and I am looking for any advice or suggestions that may help me in this venture.

Currently I have a Berlin turbo external of my sump, with the pump located on the right hand side of my sump, connected to the skimmer through a bulkhead on the side of the tank and then the skimmer return is sent back to the sump. The feed to from the tank overflow enters the sump on the left hand side of the tank, and thus, by the time the water in the sump actually reaches the skimmer, it has had a chance to settle which drastically reduces the skimmers effictiveness.

http://reefcentral.com/gallery/showphoto.php?photo=62885&papass=&sort=1&thecat=500

You can see the input on the left, and the pumps on the right.

http://reefcentral.com/gallery/showphoto.php?photo=62884&papass=&sort=1&thecat=500

This is a view of the skimmer and return line.

Anyhow, what I am looking to do is build a skimmer that attaches to the feed from the tank overflow that will drain from the overflow, into the bottom of the skimmer (no pump / powerhead due to gravity), and then at the top of the skimmer, it will feed into the sump. Although the below drawing does not show the airstone, it would be located at the base where the feed enters the reaction chamber.

http://reefcentral.com/gallery/showphoto.php?photo=62888

The advice or suggestions that I am looking for are initially if this is even possible to use effectively, and if so, has anyone has had any success with this type of skimmer.

With the idea that I have, all of the tank water would pass through the skimmer prior to entering the sump. The tank that this will be attached to is a 135gallon reef tank that currently needs a better method of removing the waste that travels into the sump, and a better method of skimming. (there is a buildup starting in the first chamber of my sump). Any and all suggestions are welcome!! Thanks

Andy
:fish1:

[Inflames]

Any reason why you choose an airstone over a better method like needle wheel or air injection? Question: how will the water on the right side get to the sump? From the pic it looks like it will just recirculate into the injection chamber again.

[RobinsonFam1]

im not sure if you would have enough flow or pressure. i have thought about doing this as well but held off for the same questions.
i still beleive that using a pump would be better.
what size of tank is this?
what would the height of the gravity be?(from overflow to skimmer)
what size of line would you use to feed the skimmer?

i would probably run the input down the center of the skimmer with some sort of baffle inside to hlp turbulence. then have it drain back out the bottom than the top. control foam height and water height inside skimmer with a gate valve.
definately make this one out of clear acrylic. it would be more than PVC but atleast you would know right off if it works or not.

keep us posted! this could be an energy efficient way of running a skimmer rather than a large pump!

[Worldwithin]

First off Inflames... I am sure there are better methods out there to inject air into the reaction chamber than an airstone, what they are is what I am also looking for. As for the recirculation, the center tube and the middle tube are considered the reaction chambers. As the water travels through these two tubes, they "should" be the only ones with air in them.. Once the water reaches the third tube, it "should" be free of micro-bubbles and then drain into the sump... Remember these are all cylindrical pipes, the ones on the inside are just smaller in diameter than the outermost pipe. As for the needle wheel or air injection, I am currently unsure of the components required to create that effect.

Second... Robinson... The concept for this is that in theory water pressure would be created by gravity itself. As long as the skimmer is below the tank, gravity feeds the skimmer and as the water level rises, it passes through the chambers. Once it reaches the third chamber it drains into the sump. The base of my skimmer will be approx 4.5 feet from the output of the overflow, directly below it.
The tank is a 135 gallon.
I would probably be using 1" PVC to feed the skimmer.
As for the center input you suggest, I have seen some diagrams on those, and they just don't look all that effective in terms of contact time.

From my understanding, micro-bubble comtact time is what is necessary for an effective skimmer, not necissarily pressure. If the flow is slow enough, then more protiens are taken out, but the down side is low volume. If you make the chamber big enough to accomodate for a higer volume at a lower flow, then you kinda solve that issue. I am not intending this to be a small skimmer, possibly 3 feet tall. And again, in theory, as long as the skimmer remains lower than the overflow I will have a constant supply of water - that is until the overflow breaks suction (IE: power outage). If you think about it, take the rating of your pump, and then compare it to the rating of your overflow. I would assume that an effective pump for a skimmer generally has a smaller output with the air injected into it than your overflow does. Now if you increase the overall size of the skimmer, it can accomodate the flow rate of your overflow. (granted this is all based on assumptions).

Again my concept for doing this is that protiens float at the surface, and since the overflow skims from the surface, why not attack them directly from that.

[Devil Man]

ok why not have an air stone or 2 in the skimmer body for when the water gets to it down there it will come in contact with the air and surface the protien? if not this then why not put the airstone or 2, in the overflow box just before it goes down so that way the bubles are allready mixed in the water? does this make sense? oh and i think that this is a great idea too, it is a great way to try to be more effcient

[Worldwithin]

I am sure there is a more efficient method than an air stone. Generally air stones produce a large sized bubble vs. an injection type or venturi type bubble. But, yes the air from an air stone would work. As for the overflow box, chances are you would break the suction of your overflow.

[Afishianado]

I have built 2 of the airstone driven CC skimmers ,both were years ago. You can build a skimmer like this that will remove plenty of gunk from your system.Thick dark skimmate and lots of it, if you have enough air and have the skimmer adjusted correctly. Based on my experience with these skimmers...here are a few suggestions. These are not meant to counter anyone elses ideas or claims just to add some notes regarding my own observations. I started to build injector based skimmers based on the fact that they fit under the cabinet of the tank and can be hidden, not because the injector type were just so much better. ( although if you have the money for the gee whiz big dollar super skimmer then by all means, they rock)

Build the skimmer as big as you are willing, the taller the better for a CC type. The wider the better as well if you are pushing enough air.

Flow should be slow through the skimmer, it's all about dwell time in the reaction chamber to remove the most gunk. The larger the skimmer the longer the dwell time.

Single pass will give you the best results for CC type skimmer. Dirty water should enter the chamber at the top and exit at the bottom. moving through the chamber slowly. IMO your sketch shows a path that wastes time while the water is inside the skimmer. again,IMO, the entire body of the skimmer should be one big dwell chamber. Be sure to diffuse the flow coming into the chamber so the turbulence created there does not hamper foam production.

Air should be pushed with airstones at the botom of the chamber, as much air as possible, change the stones often, maybe 2 weeks. You will want to air pumps that are more powerful that what you think. General rule, you CAN NOT have too much air. The possibility is there but only if you where using a tool quality compressor running full blast and pumping it into a small chamber.

Just my $.02

Chris

[Inflames]

How will you change airstones?

[Afishianado]

usually the airstones are attached to the airline via a long rigid airtube that enters the skimmer at the top, through the collection cup.

[Inflames]

hmm. well have fun changing air stones. After a year of that you could have spent as much as a good skimmer costs.

[Afishianado]

I won't disagree with you about the use of the airstones. They are not cheap over the long run.

It used to be the only way.

I only wanted to point out that it can be done and show some of the things that I found worked best.