Downdraft Skimmer in my 10G Sump

[captbunzo]

I ran across this thread last week on downdraft skimmers. After some thought I decided to give this a try. So this last weekend, I put something together and installed it in my tank at lunchtime today. The results seem to be good as foam is building nicely and skimmate seems to be collecting as expected. At least it's brown water, so I ASSUME it is skimmate...

First of all, here is a picture of the whole thing...

To views of the top of the skimmer...

Here is a view of the bottom of the skimmer...

A funny view from the top...

Skimmate, I presume?

Everybody loves skimmers!!!

(OTHER SEARCH KEYWORDS: gravity skimmer)

 

[captbunzo]

Building Comments

Building Comments

Ok. Now here are the basics behind the construction of my skimmer.

The Box
The main box of the skimmer is sitting in a 10x10x3 section of my 10G sump. This section is where the original pipe was that drained water from tank to sump. The box itself was built to just fit in this, side to side. And then it was built to provide about 1.5 inches of clearance in the front and the back.

The box has no bottom. Rather, it sits on the bottom of the 10G aquarium in that chamber. In order for water to exit the box, the front and back side panels are 1/2 inch shorter. With my little tank, that was plenty of room for the water to float out.

The top of the box, per instructions from dugg, was built to rest about 1 to 1/2 inch below the water surface.

The Water Injection Plumbing
This part was simple. I simply made a "bulkhead" with a PVC coupler and some pipe. This was glued into the top of the box. Then I attached this to the drain via a street elbow and a screw together coupler.

Please note that the pipe fitting into the "bulkhead" at the top of the skimmer box is NOT glued. Friction is fine to keep this in place and will make maintainance easier.

The Foam Riser Tube
The foam riser tube was made out of a 1.5x8 inch gravel siphone tube from a LFS. It would have been MUCH BETTER to use clear acrylic or PVC tubing for this, but none was available. The tube was not a standard plumbing size ans required quite a bit of work to get attached to the rest of everything.

Anyhow, it is attached to the top of the box via a similar bulkhead made out of a coupler and some pipe. On the top, I have a PVC plug inserted into the top of the top, and a standard band clamp around the clear tube to hold it in place.

The Skimmate Drain Tube
The plug on top has a whole in it, through which goes the skimmate drain tube. Inside the foam riser tube there is an inverted funnel which was cut to fit fairly snug. The drain tube is pushed through that and held in place (very tightly) by friction.

This whole arrangement makes the drain tube/funnel vertically adjustable. And the funnel causes the foam to climb into the tube a little better.

The other side of the drain tube is in a standard plastic jar from Walmart.

Extra Bubbles, Please?
With drain bubbles alone, I did not have enough foam production for the foam to rise in the tube as is needed. This was expected as I only have a Mag 7 pump on the tank. That's only probably producing 200-300 GPH of water flow through the sump.

Eventually the plan to add more bubbles is a air pump with a limewood airstone. Of course, that is on order right now, so I had to do something makeshift for now.

So, we stuck a powerhead into the skimmer box with the jet pointing at the wall a bit, and up a bit about halfway toward the top where the foam riser tube is. And then we stuck airline tubing through the bottom of the cover screen for the powerhead, and put an crappy little walmart airstone on it inside the cover screen and put it on the powerhead.

Basically, this injects lots of big bubbles into the powerhead and causes them to get mangled nicely by the impeller. This produces TONS of fine bubbles.

I have also thought about reconfiguring the powerhead to have the input screen facing up and sucking water/bubbles directly from the tubulant area where water enters the skimmer box.

Also I will try just a limewood airstone when the arrive in the mail later this week.

Done with Post
That's it. Enjoy...

 

[dugg]

Very nice. I like the funnel idea, i will be looking into one myself tomorrow. Part of the problem with not enough air, is that you need more drop to the intake. It's that last drop where it gets most of it's air from. I really like the tall thin design, i think that would make a huge difference for our smaller tanks. i think if we keep up working on the idea here, we can eliminate the need for spending all that money on skimmers all together. I always feel like such a shmuck walking out the door after paying $300 for $10 worth of plastic when i buy a skimmer, and even worse when i get home and it never works. Since i set my skimmer up and got the low flow figured out, i haven't had to touch it, and it has had a very consistant output. I'm getting about a pint per week (coffee color), and i think that is quite a bit for a 30 gallon tank myself. What has your temp. change been?

 

[Travis L. Stevens]

I really enjoy these downdraft skimmers. Keep the ideas coming. I only see one little problem that you might have Paul. When pump mysteriously stops pumping (IE power outage, broken impeller, etc) where will all the extra overflow water go? It doesn't look like you left very much room in the sump to accomidate the extra water. I could be wrong, but I would rather have a dry floor in the future.

 

[captbunzo]

Thanks for the tip, Travis. I already had a little overflow last night, but not because of the skimmer. Rather, when I had previously calibrated my sump fill lines, I had done so with my power filter on. When I turned EVERYTHING off for feeding, I got some overflow. Grrr!!!

But I think I have that mostly figured out now.

Btw. I am helping setup a 90G tank in my sister's doctor office (not in the waiting room, in her actual office office). And I think that I am going to build a much nicer version of a downdraft skimmer for her. I suspect it will work great for her.

 

[Travis L. Stevens]

That's good to hear. Is she ready for a tank? It can be frustrating if you don't know what you are doing.

 

[Knyght]

Interesting.
I may have to get one of the fuge lights like yours.

:beachbum:

 

[captbunzo]

Interesting.
I may have to get one of the fuge lights like yours.
:beachbum:

I was wondering if anyone would notice my creative license.

 

[Knyght]

And all this time I was thinking it was done by one of your skimmer watchers

:beachbum:

 

[capt. insano]

can we see a pic of the skimmate it's producing and of the foam head on the skimmer?

 

[captbunzo]

can we see a pic of the skimmate it's producing and of the foam head on the skimmer?

I will try to get that up in the next couple of days. I have been experimenting with different methods for getting good foam and skimmate. Different combinations of airstones, powerheads, etc.

I should have taken a picture last week before I dumped out the 2-3 cups of nastiness that I had accumulated over the week!

 

[dugg]

Just thought of something very helpfull here. The skimmer that Wayne has on his display tank doesn't have a clear PVC riser tube on it. He uses a water or coke bottle with the bottom cut off of it. The tube fits in the bottle's neck perfectly, and you just slide the bottom of the bottle over the 2 inch PVC coupling mounted to the top of the skimmer. It also fits nicely over the coupling. Since the bottom of the bottle is under the water line, it doesn't effect the skimmer's operation if it isn't a perfect fit.

 

[dugg]

If you save this pic and zoom in, you can see the bottle and how it fits on.

 

[dugg]

HAHAHA, i have tons of water bottles that will fit this. I will never have to clean that nasty crap out ever again SWEEEEEEEET. Just pop a new bottle on and chunk the old one. That just did away with my most hated chore.

 

[dugg]

Here are a few pics of the new one i built today Paul. You can see the amount of air i have inside, and see the quality of foam it is making. It has only been up for about 8 or 9 hrs when these pics were taken. The funnel is a really great improvement.

You can kind of see to the right side where i have the powerhead mounted, facing the back about 2 inches below the intake. It points straight back at the back panel. Maxijet 1250

 

[Awright]

Great idea. I think I will try one.
Thanks,

 

[dugg]

Hey Paul, i got this thing working like a champ now. It's the skimmer in the pic, with an Aquafina16.9 oz water bottle for a riser. Cut the bottle to where when it is set into the 2" PVC coupling, the rounded part of the top of the bottle, is sitting on the rim of the PVC. Just stick the hose in the top of the bottle and set the bottle in the coupling. It took it about 30 minutes to rise up, as if maybe the residue from the inside of the water bottle was killing the foam at first. It rose up about 1/4 inch at a time and dropped back, until it had contacted the entire inside of the bottle, then it went to work. It is running very consistant. You could almost set a watch to the time it takes each bit of foam to go through the tube. It is perfect foam also, not wet, not dry. I will post a pic later when i get back home.

 

[dugg]

That is the skim it has made since i made the new skimmer.

 

[Awright]

Looks good. How long did it take to make that skimate on the new skimmer?

 

[dugg]

It is making about 1/2 to 3/4 cups per day, but i feed really heavy. I expect it will slow down some after the water gets clean. Wayne gets about 1 quart per week out of his skimmer that this is designed after.