From: mark@trident.datasys.swri.edu (Mark D. Collier)
Newsgroups: rec.aquaria
Subject: Re: Protein skimmers [M][F]
Date: 9 Sep 92 20:30:14 GMT
Organization: Southwest Research Institute, San Antonio, Texas

I originally wrote:

: I am planning to add a protein skimmer to my 160 gallon tank. I currently
: have a home-grown wet/dry for bio filtration. I have heard that protein
: skimmers are pretty much essential for tanks with inverts. Anyway, what
: are the best types of skimmers? The local aquarium shop recommended an
: Oceanic venturi skimmer, which seems like a great design, but is also
: very expensive ($280). If venturi skimmers are the way to go, has anyone
: had any luck buying just the skimmer and hooking it up to a power head?
: Also, are their any other venturi skimmers available other than Oceanic?
: Finally, what would it take to build your own venturi skimmer?
 
: To which kncarp@nicsn1.monsanto.com responded and requested routing
: to the net:

I would suggest you build your own counter current one.  You could build
a nice one for about $65 (plus air pumps) or a less fancy one for about
$25.  I built a 4" x 48" counter current for the $65 that has been working
great for half a year or more now.  The main cost was for the acrylic tube,
look in the yellow pages under "Plastics - rods/tubes/sheets" and check
out current pricing.  The cheaper version is designed the same as the more
expensive one, it just uses PVC instead of acrylic.  Besides the main tube,
you will need three flat pieces of 1/4" acrylic (one square piece for a 
base (say 6" x 6"), one rectangular piece for to top (say 8" x 4"), and
optionally a cover plate (say 4" x 4")).  You will also need a short length
of smaller tubing (say 1.25" round by 2"); acrylic looks nice, but PVC
would work fine.  Miscellaneous items include two 90 degree PVC elbows (I 
used a 1/2" elbow for input, and an 3/4" elbow for output), and some flexible 
hose that fits over the output elbow.  If I was to build mine again, I'd
probably up the input to 3/4" and up the output to 1", if I could find large
enough hose to connect to the 1" output.  A 1/2" 45 degree PVC elbow is 
used for drainage.  I'd suggest hooking a drain hose to the drain elbow and
routing the drainage into a bucket.  Last but not least, get two lengths of
stiff airline tubing, a couple of Coralife limewood airstones, and a couple
of Tetra Luft airpumps.  I'd suggest mail order for the pumps and airstones.

OK, now that you have everything, construction is simple.  If you are using
acrylic, I'd suggest you get a small container of acrylic solvent (ethylene
chloride?) and a needle applicator.  Both should be available at your plastic
dealer.  For PVC construction, normal PVC solvent will work fine.  Actually,
PVC solvent will work with the acrylic too, but it doesn't look as nice.

Construction Steps:

0) Read all directions before beginning.

1) Cut a 4-5" length of the 4" acrylic tube off an end.  This piece will
become the collection cup.

2) Square both ends of the remaining long length of 4" tube.  Place a block
of scrape wood in the inside of the tube, about 3-4"s from an end.  Find a
piece of wood that fits tight, it will be providing support as you drill.
Anchor the tube well so that it doesn't vibrate (or you WILL crack it) and
drill a hole in the side, where the block is (3"-4" from the end) for the
output PVC elbow to go.  Make the hole a little small, you want a tight 
fit and the solvent will evode the edges a bit.

3) Using the same proceedure, drill a hole 5" from the top for input elbow.
Take a hacksaw and cut the 90 degree input elbow at, or slightly past, the
elbow itself at a 45 degree angle.  This will allow you to inject the input
water at an angle into the main tube so that the water will swirl.

4) Glue the bottom plate onto the tube, and glue in the cut input elbow and
the output elbow.  The input elbow will be pointing straight out, the output
elbow should be pointing up.  Make sure you leave enough clearance between
the outer tube wall the the output elbow to allow you to attach the flexable
hose.  I believe I used a 2" length of PVC pipe inserted into the elbows to
form connection nipples that I then clamped my flexible input and output
hoses too.

5) Now would be a good time to do a basic water test.  Add a cup or two
of water into the base (after its set of course!) and verify water tightness.

6) Place the top plate so that it is evenly spaced on three sides, and hangs
over the side of the main tube on the fourth side.  Drill a hole that aligns
with the center of the main tube, sized to accept the short length of 1.25"
tubing.  This short tube will be the foam rising chamber.  Place the
previously cut section of main tube (the "collection cup") so that is is
right against the rising tube and overlaps the edge of the main tube below
it.  In the area between the edge of the collection cup and the main tube,
you will hopefully have enough room to drill the drain hole.  Verify this,
offset things if necessary and drill and attach the drain nipple.

7) Glue the collection cup and riser tube to the top plate.

8) Silicon the top plate to the main tube.  I know this is messy, but you
may want to take the top plate off every year to two to clean.  I find
cranking up my air-pumps and flushing a gallon or two of water through as
wet foam does a reasonable clean-up.

9) Attach the exit hose and raise the other end above the top plate.  Attach
a temporary hose to the import nipple and raise its other end about the top
plate as well and fill the whole system with water.  Find and patch any
leaks (you shouldn't have any, but this is a "peace of mind" step).

10) Attach airstones to stiff airline and insert both down though the 
riser tube.  I place one airstone right above the output port, and the
other about half-way down the tube.  Trim the stiff airline and attach
flexible airline so that you can route the flexiable airline out along the
edge of the collection cup.  Place the cover plate on, attach the airline
to your air pumps, plumb the input and output, and you are set.

Adjustments to the water height are accomplished by two methods.  The
rough adjustment is via raising or lowering the flexible output hose's
height.  It will end up being somewhere slightly below the input nipples
height.  Fine adjustments and foam height are controlled by using the
air production adjustments on the Luft pumps.

Heres a shot at a picture:

       =AAA=AAA=   ("AAA" are airpumps, a convienent place to put them)
	|     |
	|   | |  
       == ==| |====  (goofed slightly, riser tube should be in middle) 
	/ / |     | 
       / /  |     |
     Drain  |     ---
	    |     ---  Input nipple
	    |     |
	    |     |
	    |     |
	       .  
	       .  
	       .  
	    |     |
	    |     |
	    |     |
	    |     |
	    |     |
	    |     | ||  Output nipple
	    |     --||
	    |     ----
	    |     |
	    |     |
           =========

	   
Hope this helps!

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Mark D. Collier                      Southwest Research Institute
Senior Research Analyst              Automation and Data Systems Division
Voice: (512) 522-3437                Data Systems Department
FAX:   (512) 522-5499                Software Engineering Section
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Newsgroups: rec.aquaria