Downdraft skimmer update.

[dugg]

Sounds like a good design to me. As for the tubing, i'm not sure where to get the clear rigid tubing at. I will ask wayne where he gets his at. Not real sure about the funnel. that's a pretty short riser, but it may work. I wouldn't do any glueing until i got it working though, so if you need to redesign it you can. Wayne had a good idea for low flow systems to boost the bubbles and flow. He said try placing a pump in the sump and plumb it in to the drain plumbing with a Y connector. That way you get high flow in the skimmer without flowing it all through the tank. On a small setup like this one, i would think a good size powerhead would do the trick.
One thing about this design as opposed to a normal skimmer design, is that all of the tank water goes through it every time it passes through the sump, instead of a pump sitting in the sump picking up random water.

 

[dugg]

I found 1 cheap way to get 2" clear tube. It's a gravel cleaner 22" X 2" tube on it.
http://www.drsfostersmith.com/product/prod_display.cfm?pcatid=12752&N=2004+113165

 

[captbunzo]

First, here is another option someone recommended to me in another thread somewhere on reefcentral...

http://www.drsfostersmith.com/product/prod_display.cfm?pcatid=3902&N=2004+113159

And at my icky little LFS, I found a 8" long x 1.5" diameter siphon kit. That, paired with some PVC will probably work.

A couple of questions.

First of all, you commented about the difference between this and a regular skimmer....all tank drain water...etc. Is there any problem with all tank drain water passing through the skimmer? Sounds more efficient, to me.

Secondly, I have a question concerning the main chamber design a little. I have been thinking, because of the fit of things, that I should probably make the main chamber of the skimmer take up only the top 2/3 of the input chamber in the sump. Otherwise, the opening to allow the water to flow into the sump would have to be on the same side as the injection pipe, and that would seem to defeat the purpose.

That make any sense? That was a horrible explanation.

Anyhow, thanks for the input. I am going to build it this weekend when a geek friend of mine comes to visit.

 

[Okireef]

I made one using the above dimension and after 3 days it was skimming .....not very well but it was skimming. Now, I have a mag 7 pushing up almost 6 feet so I am not sure of the actual flow rate but It's enough that I wouldn't want to put a bigger pump on. I would have too much flow in the tank if I went any bigger. The skimmer was allowing the bubbles to combine, and as the post states the bigger bubbles going into the stand pipe are very loud. I added a pump and an air stone to add to the turbulence and it did better but still not what I need. So, I cut the width dimension down to 3 inches. Now there is a much smaller area for the bubbles to get big in and a tighter area for more turbulence. Over night it put out about 10x what the bigger one did in three days. The skimmate was wet and green so I moved the tube up and it is still pumping out foam. This is a really neat design and I can see how a tank with 1000gph flow would really make this thing go.
OH!!! My temp has dropped about 2 degrees since removing my other skimmer. Iââ"šÂ¬Ã¢"žÂ¢ll let you know if things change

 

[dugg]

Great to hear !!!! Thanks for letting me know how it worked out for you. Mine seems to be getting better as time passes. I have been thinking of building me another one that is smaller also. I guess you just made up my mind . That is the same temperature drop that i saw also 2*. Feels good replacing 3 to 400 dollars worth of equipment with $10 doesn't it? lol

 

[dugg]

That was what i was meaning about all of the drain water having to pass through the skimmer, much more efficient i would think.
The chambr idea sounds fine to me. Just remember that the top panel of the skimmer needs to be 1/2 to 1 inch below the water surface. Actually Wayne keeps his set at level with the surface, but he has such tremendous flow that his box would stay filled if it was 2 inches out of the water.

If anyone has questions tomorrow, be patient lol, i am spending the day at sea world with the wife and my step grandson, while his mom has the new baby. I will most likely be tied up pretty good this weekend . July 29th will never be the same again lol, Wife and 2 grandkids all having thier birthday on the same day, oh my god, that is going to make for a busy day every year from now on lol.

 

[likeavillain]

I don't understand how you can get skimmate in freshwater. the necessary smaller bubbles don't form in freshwater b/c there isn't enought surface tension?

 

[likeavillain]

sorry dp

 

[dugg]

I really don't think or claim that it will skim fresh water without some help, but with the dye in it, it skimmed and with the slimecoat declorinator added to it, it skimmed very well. If it were just regular fresh water, i don't think any skimmer will skim it. I was shocked to see it actually had skimmed it myself. Here is a picture of it working with fresh water, with only the dye in it, and a limewood air diffuser.

 

[bkiba]

how do the down draft skimmers work? Any good links - thanks

 

[dugg]

They work totally off of the overflow current, creating turbulance and air, with no added pumps or air on a large high flow system. On a smaller system with less flow, you add a powerhead and airstone, to help it produce the same effect. Basicly using gravity as a pump.

 

[bkiba]

so it is water rushing (from the return or some other gravity feed) into a large box where it whooshs around and makes foam?

thats it?

and this works ?

 

[dugg]

Yes , that's exactly what it is, and yes it works good.

 

[Gwalker]

Imagine the foam I could get from my two 3" return lines on my main salt system. It runs about 10,000 to 12,000gph through those lines! I think maybe the design would have to be upgraded a little bit, size wise!

Gary

 

[dugg]

That thing would scrub the water crystal clear. I bet you could build one that would skim 10x what the one in your pick does, because it would skim the entire system on every pass instead of randomly like a pump does. Finding 3" clear tubing for the riser might be tough though. With that much flow, you may be able to build it with 2 or 3 risers. Just think of the electricity you would save, and the temp difference it would make.

 

[Gwalker]

Yea, but the coolness and electricity would be minimal in respect to the 2hp, 9amp main pump and the 1hp, 3amp bio-pump. In a 2000 gallon system the three sedra 9000's don't add up to much affect on things compared to that.

Gary

 

[dugg]

You could use a 30 gallon cube, with an acrylic top. Dual 3" inputs with a 4" riser and a 1 to 1 1/2" hose going to the collection bucket. Just notch out about 2" of the bottom of one side for the exit water. You would be producing fish poop coolwhip lol.

 

[DoobieNaq]

So when you set up the powerhead it is actually pushing water into the exit hole which is cut into the bottom of the skimmer. Does this make the waterflow and powerhead work against each other?

Also what size and brand airpump do you use?

BTW, this looks like a pretty good first skimmers for a NewB like me. However, I am thinking of incorporating it into my sump/refugium (1st chamber) - Good idea?

 

[dugg]

Yes i have a maxijet 1250 powerhead sitting in the exit hole facing into the skimmer. It just causes turbulance and also give the water more contact time.
I am using a luft airpump, and a limewood air diffuser. I think building it into the sump is a good idea myself. I know mine is working real good, and i know for sure that i can find better uses for the 2 to 400 dollars that normally would be spent on a skimmer.

 

[captbunzo]

If you do build one of these into your sump, I would recommend adding a "bypass" that would allow you to optionally drain into either the downdraft skimmer, or drain directly into the sump. That would give you the ability to "turn off the skimmer" without having to completely stop water running through the sump/refugium.

I have just completed mine, which seems to be working great so far. I will post some pictures soon.

(NOTE: I didn't add the bypass piping as I just don't have enough room under my tank. I did some silly things with my stand that make this difficult. Plus, it's only a 29G tank...)