Setting the Skimmer
To the left is a picture of what your skimmer box will look like once the
pump and all the filtering components are installed.  The water will flow
through the skimmer door (or weir) opening on the right side of the
skimmer box and into a large, mesh net.  This net will trap any large debris
like leaves, excess fish food, etc.  You will need to check it regularly until
you get a feel for how often it fills up during the different seasons of the
year.  Dividing the mesh net half of the skimmer box from the pump half of
the skimmer box is a series of filter brushes and a PVC support frame.  This
frame holds the sides of the skimmer box in square when you backfill
against the skimmer box with dirt.  On the other side of the support frame
is the area where the pump sets.  In this picture you can see the white PVC
check valve assembly which connects the pump to the flex pipe that runs
the water up to the filter box.  The check valve assembly only allows the
water to flow one way - away from the pump.  If the pump is shut off for
any reason, the trap door on the check valve assembly automatically closes
to prevent the nasty water in the filter box from backflowing into the pond.
Step 8:
In the picture to the right, the skimmer box lid is in the place where we're going to
put the skimmer box itself.  Notice how the plumbing from the bottom drain is going
to come up directly under the skimmer door opening.  
If you are installing a bottom drain (and you are, aren't you), you will also have a 3"
bulkhead fitting, a 3" threaded male adaptor, and a 3" PVC 45º connector.  These
will be installed on the front of the skimmer box under the door opening.  
Hopefully, the factory already drilled the hole for you, if not, you will have to cut
in your own hole.  Using a Roto-Zip and one of the washers from the 3" bulkhead
fitting as a template, use a marker to mark the inside perimeter of the "O" ring in
the center of the area below the skimmer door opening along the outside edge of
the marking.  Once you have made your hole, make sure your bulkhead fitting fits
through comfortably but snuggly.  Silicone the threads of the bulkhead fitting and
screw it into place.  NOTE:  The threads on a bulkhead fitting are opposite of the
PVC adaptor.  This is so when you're tightening the male adaptor into the bulkhead
fitting, you're not simultaneously loosening the bulkhead fitting.  Tighten your
bulkhead fitting down as hard as you can.
Next, on the outside of the skimmer box, coat around the inside of the bulkhead
fitting and the threads of the male PVC adaptor with PVC primer and then PVC glue.  
Screw the PVC male adaptor into the bulkhead fitting right away.  PVC glue sets up
REALLY fast!  Now you can set the skimmer box aside while you dig the place for the
skimmer box to set at the pond edge.
The skimmer box itself is shown in this picture, back behind where we were
working.  Even though the bulkhead fitting and 3" male adapter are not yet installed
in this picture, remember, the flex pipe needs to enter the right side of the skimmer
box, so don't set the lid dead center from where the pipe comes up.  
Take your shovel and mark out the corners of the lid, then remove
the lid, set it off to the side, and start digging.  The hole will need
to be just a bit bigger than the skimmer box so that you can make
adjustments, and
the sides must be straight up and down, taking
care to clean out the corners.  (In the picture to the left,you can
see the bulkhead fitting just below the skimmer door opening.)  
The ground beneath the skimmer box must be completely level.  
To accomplish this, you can dig it out a little deeper than it needs
to be and then backfill it with enough sand to bring it back up to
the right level. Check that the skimmer box is level side to side and
front to back (it's o.k. if the skimmer box tips forward a little, but
it MUST be level side to side.)  Now get into the skimmer box and
wiggle around a bit to determine if the box is truly level, and if it
is "tippy" one way or the other.  You may need to take it back out
of the hole several times to get it level and securely set so it
doesn't tip as you're backfilling against it.
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The skimmer box needs to be set deep enough so that the second screw hole from the top is at the finished water level,
therefore, the hole for the skimmer box needs to be a little deeper than your first plant shelf.  
NOTE:  In this picture, the 3" male PVC threaded coupling is not yet
installed.  Before you backfill against your skimmer, make sure you
have the 3" male PVC threaded coupling glued in and screwed down
Still standing in the skimmer box, backfill dirt over the pipe you just installed, pack it down and smooth it out.  Once the liner is
in place, you won't even see the flex pipe.  Also, if you have filled your pond up to just below the top plant shelf, as suggested
in Step 7, there will now be enough water pressure against the liner to throw some dirt down around the flex pipe coming up the
side of the pond.
You can now poke holes through all of the pre-drilled
holes in the front of the skimmer face plate and
through the liner so that it comes out the appropriate
hole on the skimmer box itself, and screw each nut on
from the back, tightening them down as much as you
can by hand as you go.  Work your way all the way
around the skimmer face plate.  Once all the screws
are installed, go back and tighten them down as hard
as you can using channel-lock pliers and a Philips-head
screw driver.  You should end up with one extra
screw, washer and nut, which the company provides in
case you strip or lose one.  When you have the face
plate installed and every screw is tightened down,
take a utility knife and cut the liner out of the door
opening from the inside of the skimmer box.  You can
now fill your pond up the rest of the way and put all
the guts into the skimmer box as described at the
beginning of this page.
You are now ready to silicone the face plate (or weir) onto the front of the skimmer box.  Cut away any extra underlayment
so that it does not touch the skimmer box anywhere where the face plate will go.
 Then pull your liner up the front of the
skimmer box.  Be sure you have enough liner to cover the plant shelf, into the corner where the shelf meets the skimmer, and
up the front of the skimmer box smoothly.  It is important that you don't skimp here and pull the liner too tight at the bottom of
the skimmer box or the weight of the water on the liner, once the pond is full, will cause the liner to pull away from the face of
the skimmer box, and will cause a leak that will be hard to fix.  The way to make sure you have enough liner at the front of the
skimmer box is to stand inside the pond on top of the liner, with your toes right up next to the skimmer box, and drape the liner
over the top of the skimmer box from there.  When you're sure everything is positioned correctly, making sure there are no
folds in the liner under the face plate, fold the liner back and run a thick bead of silicone around the outside of the opening on
the skimmer.  Reposition your liner so that it is smooth across the face of the skimmer box and press the liner against the
silicone.  Now take the face plate and line the holes in the face plate up with the holes in the front of the skimmer box.  Take a
awl or a Philips head screw driver and poke it through the top corner hole of the skimmer box, the liner, and the top corner
hole of the weir.  Insert your first screw and washer, and tighten down the nut on the inside of the skimmer box.
Once everything is at the right depth and completely level, stand in
the skimmer box again and backfill against the back and sides of the
box.  Most of your work now will be done from inside the box, so if
you find sitting on the edge of the box uncomfortable, grab the lid
and set it across the left side of the skimmer box for more
comfortable seating.
We are now going to be attaching the flex pipe from the bottom drain
to the front of the skimmer box using the 3" PVC 45º coupling.  
Measure how far it is from the male adaptor to the flex pipe, keeping
in mind that you will need to add 2" to each end for the pipe to fit in
the deep socket coupling properly.  
Cut the 3" flex PVC that is coming up from the bottom drain so that when you attach the 45º coupling onto it, it will direct the
short piece you will be installing from the 45º coupling directly into the 3" male adapter at the front of the skimmer box.  
Measure and cut a short piece of 3" flex PVC to connect from the 45º PVC coupling to the 3" male adapter at the front of the
skimmer box.  Clean any dirt off the flex pipe and silicone the short piece to the main drain line.  Now silicone the short piece
into the male adaptor on the front of the skimmer box.