Mini Skimmer

That "fatter" piece of pvc, just after the water exits the box, is an expansion repair coupling.  It's completely water tight and telescopes about 3 inches.  The tee on the outlet is needed as a syphon break.  I've made skimmers in the past with valves on the outlet (like the ETSS skimmers), they work good too.  The expansion coupling is a bit more compact.

Some specs:

• currently powered by a RIO 2100
• 1/2 Mazzie venturi
• 3 1/2 inch diam x 12 inch long main chamber
• 2 inch diam x 5 inch long secondary chamber
• 6 inch diam collection cup

The water exiting the box is for all intents and purposes, bubble free.  There are bubbles where it flows back into the sump, this is due to the syphon break (it sucks air down the tube).  These are big bubbles and are easily removed in the baffles.

I used extruded acrylic tubing which means it's only 1/8" thick.  In order to get a good glue line, the holes in the box and flanges were cut to the outside diameter of the tube and the tube slid into the hole.  This gave a 3/8" glue line at the box and a 1/4" glue line on the top flange.  Both the inlet and outlet from the box were drilled and tapped to accept pvc threaded fittings.  As you can see, I never found nylon thumbscrews, so I just used wingnuts.  A 4 inch diameter o-ring is used to seal the top flange.

1/4" cast acrylic will run about $3.50 - $4 per square foot (3/8" a little more).

6" tubing was about $8 per foot, 3 1/2" at about $4, 2" at about $2.

Call Regional Supply for exact pricing...

The potentially expensive item is the venturi.  I picked up mine used from one of the LFS for about $15, but they can run upwards of $25 - $50 (Kent Marine sells one (1/2") for about $20 that I would have used if I hadn't found mine).  If you're building a large skimmer, I'd use a Beckett Foam Head.  I bought one at Home Depot for $7.  Beckett skimmers need a big pump to function properly.

Yes, your understanding of skimmers is more or less accurate.  The difference in skimmers is how the air bubbles are created.  You can use an air pump and air stone, venturi, down draft nozzle, beckett head, venturi on the pump suction and paddle wheel on pump, ect.  The other, imo, important design consideration is contact time.

Why not build both!  I like using a skimmer but would really like to add a refugium to my system too!  Both projects require some woodworking tools to cut the material... anyone can glue .

If you don't have tools, I think Reginal Supply will cut for you.  If not I could cut out some pieces for you.  Good luck!

I see the tubes and all the bubbles but have no idea how it works or fits together. Do any of you have written designs (drawings, specs, etc) on how to build a skimmer and what the principles are to tweak the designs for increased efficiency? Links are ceartainly welcome.

Cortney,

Here's the same photo as above with explainations:

There are many different ways to make bubbles, what you see in this picture is a venturi nozzle.  IMO, what makes a good skimmer is lots of fine bubbles and lots of contact time.  Generating the bubbles are usually not a problem but the increased contact time means a longer/bigger skimmer.  Obviously, there must be compromises in the design.

Do a search from google for "protein skimmer", you'll get hundreds of hits.  Here's an old (but fairly good) site regarding design (also follow the links within the article):

http://www-2.cs.cmu.edu/~cap/raid/skimmers/orig_dd/index.html

  I cant get that link to work on my puter lets try it a again.http://http://reefcentral.com/forums/showthread.php?s=&threadid=167257 I meant oz reef page sometimes I get a little disoriented I think yours is cool I am buying the materials this week I was wondering if that acrylic extruded comes in any thicker wall thickness? Do you think with the 1/4 inch glue seam is good enough? I want to build a quality skimmer but I cant afford the cast acrylic unless someone wants to go in on a 4' lenght with me? Thanks for all your help jfinch

maxiumus89,  you need to get rid of the extra http:// in you're linked address.  Here's the link:  http://reefcentral.com/forums/showthread.php?s=&threadid=167257&highlight=cheapreef  This skimmer uses the same principle as the downdraft for air/water mixing and usually requires a larger pump... although he does seem to be getting good foam with just a Mag 7.

I didn't feel comfortable with 1/4", but you might .  That's why I used 3/8" material for the top and outlet side of the box.  The hole for the riser was cut to the outside diameter of the riser tube.  The riser tube was then slid into the top and glued giving a 3/8" glue line.  1/4" is problably fine, ymmv (abreviation for Marcus).

Give it a go with extruded.  My gut feeling is that it doesn't make much difference in the thinner material.  The problem with extruded (in water), as it was explained to me, is that it tends to absorb more water then cast causing it to swell and weakening the glue joints.  A 1/4" glue line is not going to move as much as a 1/2" (similar to the idea of cross grain gluing in woodworking).  The other problem with extruded is crazing (hundreds of micro cracks right at the glue line).  IME, extruded acrylic almost always crazes some... not sure it effects strength, but it doesn't do anything for asthetics. 

   Jon have you ever thought about laminating two .25 sheets together to get a .5 for the box I have alot of .25 or .375 scap I could laminate I would make it .75 wall if it would work and I dont see why it wouldnt do you?

  I would agree on the over kill but I wanted to make a panel of 9"x7" if I laminated them together out of .25 or even .375 material what would I use for glue do you know? that would be the top of the skimmer box so I would have atleast .5 or .75 inch of glue joint. I could laminate the small sheets to gether and cut to size. I am asking you what glue or glues should I purchase I plan on buying the tubing and glue tomorrow at deviles. thanks for answering all my questions jon