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Undertheradar

Wetworx Nano-skimmers!!!

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Undertheradar

“DIY smallest skimmers”

 

The DIY nano-skimmer was first posted in response to this thread: http://www.nano-reef.com/forums/index.php?...opic=30941&st=0 . I had been tinkering with the idea for the whole of last summer, realizing that a good skimmer for a nano did not exist...or the ones that were effective were rather cost-prohibitive and oversized. Despite the various versions that have been made since based on the aspirating-venturi method, the winning design of the ‘smallest’ was found months ago. It measures only 2.5” wide, 1” deep, and 14” tall. It sits on the back of an aquarium and can handle up to about a 20gallon, but is really ideal for a 10gallon. The pump I use is the Hagen Hi-Spec 1000 powerhead, which is no longer made by Hagen, but can be found being made by various other manufacturers with the same design. You still might be able to find the Hagen powerhead under it later model designations…aquaclear 101 or Aquaclear 10. A worthy substitute for this pump would also be the maxi-jet 400. The Hagen pump pumps about 80gph, and the maxi-jet about 106, but that’s close enough considering how much of the flow is lost in the back-pressure of the injection system (you’ll see later).

 

So first I am going to show the injector/spraybar based DIY, then the aspirating-venturi which outperforms the injector but is slightly larger, then the other variations on the two basic concepts such as an ‘in-sump- version, and larger versions.

 

Spraybar Nano Skimmer: Minimum Tools:

1. Plexi cutting equipment. I am fortunate to have a large plexi/glass cutting machine in the basement, but most of you might not be able to use one. The next best thing is a plexi-knife, suitable metal straight edges and clamps, and the edge of a sturdy table to cut the acrylic using the score & snap method. This method is not going to be explained here, but is similar to how sheet glass is cut and has been detailed on the internet many times over…just do a search. Table saws and other power equipment can be used as well, but those of you who would rather use a table saw, have one, etc...know enough to not bother hearing me talk about it. Worst case, if you don’t have the abilities, confidence, tools, etc…to cut your own acrylic, most any glass shop or plastics distributor can sell you the pieces you need cut…just know you might pay more in labor than the plexi is worth.

2. 100-150 grit sandpaper.

3. weld-on #3, and applicator bottle w/ fine tip.

4. clamps? These are optional, but do help. I like to use a piece of extruded aluminum ‘L’ channel to help hold the pieces for the corners…combined with small carpentry clamps to hold pieces together for a few minutes while the weld-on dries. Weld-on 3 dries fast however, so this is not needed as long as you dont mind holding the pieces for a few minutes.

5. Drill & drill bits. Sizes may vary.

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Edited by Undertheradar

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Materials:

1. 1/8” Acrylic, extruded or cast (cast is stronger, but this project is so small it doesn’t matter). You can go to Home Depot and get the 11x14” piece for a few dollars.

2. 6” piece of ½” ID x 5/8” OD flexible hose.

3. 80-100gph-ish powerhead. This was covered above and is the only real expense in this project.

4. CPVC parts: ½” CPVC (not PVC), this is important because its OD is 5/8”…much smaller than PVC. You will need less than 6” to make one injector, but might want to make a few to get one that is ‘just right’. Besides straight PVC, you will want a cap and elbow.

5. washers. I use #54 o-rings from HD, but most ½” ID washers will be fine.

6. air hose, and plastic air valves (who doesn’t have some of these lying around anyways?!?)

 

Assembly of the main skimmer body should be based on these specs:

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I have mentioned that removing the 1”x2” piece (dark blue) showed little change with regards to micro-bubbles. One could also cut an extra 1”x3” piece to use as a lid as well. To make this easier, the side pieces (dark red) should be 1/8” shorter, so the lid slides in between the front and back 2.5” x 14” pieces with ease. Also, this skimmer doesn’t need to be this tall. It would result in a very slight increase in micro-bubbles in the main tank, but shrinking the skimmer to 11” tall works fine as well.

 

Order of assembly:

1. Cut the plexi. I usually just cut the front and back larger pieces, then about 4 or five strips of the 1”x14” variety. This allows you to pick the closest matched pieces for the ends and in between…as you will find that with a skimmer this small, varying results due to inaccuracy of cutting devices are more noticeable. Then I also cut the bottom piece…it can be larger than the 1.25”x2.5” spec I give. It can be 1.5” x3”…giving a slight lip around the bottom. This makes bonding it easier later on, and allows for a spacer between the bottom of the skimmer and the tank.

2. Sand the plexi. The two larger pieces don’t need it, but I sand the 1” strips on their sides very briefly. This squares off the bonding surface that might otherwise be angled from the score & snap method used to cut it. This also roughs up the edge to make it nice and porous…making bonding that much stronger and easier.

3. Bond the main body…starting with the sides (red), then the long divider (dark green), then the injector baffle (olive/khaki), then the collector cup bottom (light green). The sides are easy, as well as the main divider (dark green), but the injector baffle might be tricky to get just right. The bottom of the divider can be as close as 3/16” up to about 3/8” from the main divider (dark green) and still make a good injector port. I also make sure to place a piece of CPVC between the pieces to make sure not to make the chamber too small. As for the top end of this piece, I try to make it come as close to ½” or ¾” from the side wall (red). This area will vary depending on how you want the skimmer to skim. A taller area will result in dryer foam. And shorter will result in wetter skimming. The width of the foam riser area might start out wide, but should end up tapering so that as the foam rises it eventually gets blown out the top…unable to fall back in.

4. Drill the skimmate drain. This hole’s size may vary. You can make it either smaller to be able to just shove a small air-valve in…or large enough to directly squeeze the air-line in…placing the valve on the tubing down the line if at all.

5. Drill the air inlet. This can be a small 1/8” hole, or larger…like ¼”, to fit another air-valve into the regulate the air. Your call. I do not post these specs because they are up to you and depend on the exact size of the air-valves and tubing being used.

6. Drill the injector assembly’s hole. 5/8”. For such a large hole, I would suggest starting small and using spade bits (usually for ceramic) to widen the hole until ½”. Then I use a tapered sanding stone on a drill to slowly widen the hole to a perfect 5/8” w/o chipping or cracking the acrylic. I will show this later.

7. Assemble the spraybar injector. I will show this later.

8. Drill the overflow outlet. I make it ½”, starting with the highest point possible. Turn the skimmer on to see how it works, turning off only to drill. This might make the water level in the injector chamber too high to inject air…but then enlarge the hole downwards until the water level in the injection chamber is about 1/8” below the spraybar.

9. Glue on the outlet pipe, HOB holders, etc. I use 1” OD x ¾” ID acrylic pipe for the overflow back into the tank, simply gluing it over the overflow hole made in step 8. To this I add a small lip at the bottom to prevent the water from dripping outside the tank. I also glue a bracket to other end of the skimmer to help hold it on the tank. I will show this in detail later. You might as well put a lid on now if you want to.

10. Turn it on, look for leaks to go back and glue. If needed, Weldon 16 is a thicker weld-on that can be used to plug leaks…even after the skimmer is assembled. I apply it to a corner inside the skimmer, then let gravity pull it down along the whole inside corner I am trying to seal. I have done the whole inside of skimmers like this after they have been assembled…its like playing that old game where you have to tilt the board to get the marbles to fall in the holes or go through the maze. I just keep tilting the skimmer in various directions to get the bead of weld-on into every corner.

If the pipe/injector assembly leaks around the CPVC, use some silicone lubricant made for faucets to make the washer more effective. I just drop the whole washer in the silicone, getting it all over…then I reassemble the injector and wipe off the extra.

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Now here is an alternative. It is the reverse-venturi or asperating method. The first skimmer is an injection skimmer, using a spraybar to inject pressurized water into a water body to make bubbles...very much like AquaC skimmers but with a spraybar and multiple injectors rather than a single nozzle like on a garden hose. This skimmer is more like a Euro-reef, ASM, Bubble King, etc...in that it uses the pump as the mixer of the air and bubbles, and then shoots the mix into the skimmer. I started this because in order to produce these I had to make sure I wasnt touching AquaC's patent on injection technology...which is silly considering its really just another take on venturi injection. The other reason was that I noticed the powerheads that were running the spraybar injectors werent made for pressure applications, and were seemingly loosing their steam after a year...perhaps the magnets were wearing out.

 

The good news is that the reverse venturi method works better anyways. It makes twice the bubbles, finer, and doesnt create pressure problems like with the spraybar injector. And it means you wont have to clean the injector holes anymore.

 

Here is the diagram of what changes:

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Edited by Undertheradar

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Notice that the skimmer is wider (3" instead of 2.5"). This is because of the increased bubble count. Notice the lack of an air inlet hole on the injection chamber...this is because the air is coming in through the pump intake now, not the skimmer's main body.

 

These dimensions are based on the pump I am using...if you use a larger one, you may need to make the skimmer wider or taller. For a maxi-jet 400, you would prolly want to make it 3.5" wide.

 

The following is my step-by-step assembly of the above skimmer. I made this one 18" tall for testing purposes (too see if increased height, and if so how much, would help reduce micro-bubbles>>NO). This skimmer is fine at 14" high however.

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Well, heres my cutter. It cuts sheet acrylic and glass in a snap. This might not be what you have, but most glass shops do. Note the blue sheet...this is the regular 'acrylite' brand from HD. That sheet is the one getting used.post-7237-1132334988_thumb.jpg

Edited by Undertheradar

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FWIW, that machine is really a 6'tall x6' wide inverted 'T' with dual poles as a track for the blade holder. Its big. It costs something like $1500 new...got mine for $50. Below are some of the skimmer designs that show how things have changed...

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Edited by Undertheradar
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alright, so we have a bunch of pieces...extra 1" strips that will get cut into smaller parts after sanding...

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I sand the edges of the skimmer to prepare them for bonding...

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or you can tape a bunch together so that sanding them will result in the same size strips being made...

post-7237-1132335215_thumb.jpg

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here are some tools I use. plexi-blade for cutting the 1" lengths...weld-on #3...applicator bottle...clamps...extruded aluminum 'L' channel...

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I use the aluminum to hold the pieces square to the outside edge when bonding. Then I just use porosity of the sanded edges to soak up the weld-on as I apply it in the inside corner...starting from what will be the bottom edge of the skimmer (to make sure the eventual bottom is square), and working my way up to the top.

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working my way to the middle...

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and then the other side...

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then I use the cutter and straignt edge to cut the shorter pieces...

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and then I start on the internals...first with the main divider...

post-7237-1132335548_thumb.jpg

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then with a piece of CPVC as a guide, I position the injector baffle. If you are doing the injector version, you want to leave enough room for the pipe as well as a little more for air.

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then the last internal piece...

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and then I use the aluminum channel to help glue the front on...sorry for the crotch-shot guys...LOL.

post-7237-1132335734_thumb.jpg

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then I start to drill the spraybar's inlet. I start with an 1/8" guide bit. I dont bond the bottom of the skimmer on yet because its easier to shake out all the shavings if it gets done later...

post-7237-1132335789_thumb.jpg

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then a 1/4" spade bit that is usually used for ceramics...

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and then a 1/2" one...

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then I use a sanding bit made by wolfcraft. I make the hole bigger and bigger...stopping every few seconds to see if I can fit the CPVC through the hole until it does. Repeat and do the other side...

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then stick that CPVC through and cut a length that lets the pipe stick out about 5/8" on both sides. This might be too much, but you can always sand down the pipe ends to fine-tune the length.

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and these are the washers I use...11/16 x 9/16 x 1/16 #54 O-ring. Any that are about this size work well. Slip them on either end of the pipe, pushing them against the skimmer body. Then slip the endcap and elbow on either end to hold everything in place. If the washers are not snug, the pipe is too long. Take it out, sand it down a bit, and try putting it together again. Repeat this until the washers are snug between the acrylic skimmer body and the endcap/elbow fittings.

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Edited by Undertheradar

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