About three years ago I decided
to have a Koi and Goldfish pond in my back yard. I wanted it to be like a
small eco system so I would not have to spend a great deal of time on
maintenance. I know now that some sort of filter is required because of algae.
I considered one with a water pump that pulled water through a sponge type
material. It was expensive, and I did not really want to try to keep
ahead of the fact that the filter will slowly become clogged with debris, need
cleaning, and at the same time will cause the pump to work harder and harder,
or even burn up the electric motor of the pump. So I spent many hours
thinking of other alternatives.
These will last depending on leaves, grasses, algae, and such that gets filtered out of the water from the bubbles flowing up the air chamber with the chimney on top. The indicator will be the air bubbles that you see on the surface of the pond. Mine last about 3 months, and when I change them, I save the old ones. I wash them under a faucet, scrub the material against itself and do some cleaning by hand, but no soap. I hang them in a sunny place to dry out and if needed later I'll use a medium stiff brush for the final cleaning. They are reusable to the point that since I started using them over 3 years ago I have not had to replace any.
I had already purchased an air
pump for ponds from pondliner.com, model AP-20 PONDMASTER (worth every
penny). I wanted to insure enough air
was available during the hot summer months, as well as keeping the water slowly
moving. Before that I was
using an aquarium pump and had a stone bubbler submerged. I purchased that pump at PetCo,
model AC-9903 for 13 – 106 gallon tanks, a great pump but not for ponds.
There is something about the pressure caused by the depth and volume of the
water that makes it necessary to have a “for real” pond air pump. I also realized that when I
had kept an aquarium, it was using an under gravel filter system that
circulated the water with bubbles from a pump. I had to figure how I
would apply this to my current situation.
I came up with a design using PVC
pipe and here is what I did:
Materials list:
4 inch PVC pipe – 1 piece 5
inches long
4 inch to 2 inch PVC reducer – 1
2 inch PVC pipe – 1 piece 7
inches long
2 2 inch PVC couples
Now the ½ inch PVC pieces:
2 plugs (slip) with
hex head
5 T’s (slip) Slip means smooth inside for gluing, not threaded
1 T (center is
threaded with ends slip)
1 elbow (slip)
1 adapter (one end slip / one end threaded outside)
1 adapter (one end slip / one end threaded inside)
2 – 8 foot ½ inch
pipe
1 PVC cutter (looks like a pair garden pruners)
1 small can of PVC glue
1 ½ inch plastic sprinkler hose attachment
piece, threaded
1 Army cot mosquito
net cover (to make filter bags)
Plastic zip ties about 14 inches
long
Total cost is approximately $35.00,
depending where you shop. I went to Lowe’s and
an Army Surplus Store. The 4 inch
pipe is the bubble chamber and the 2 inch pipe is the chimney. You might
get a plumber to give you his discarded pieces.
Please note that my pond has a top
measure of 18 feet by 14 feet with 4 sides that slope at approximately 45
degrees down to the bottom. Here it measures 4 feet square on the flat,
and is 4 feet deep with lily pads. My design is for the filter to sit on
a slant rather than flat on the bottom. This means that the measures and
assemble may differ in your situation depending on where it will be positioned
in your pond.
To get started I cut two (2) pieces
of ½ inch pipe about 5 inches long. These are to be the chamber
supports. I measured about 1 inch from the end and marked the
pieces. These pieces should be longer if your filter is sitting on a flat
bottom which makes it perpendicular to the base. This position would
require the bubble chamber to be raised enough for the air hose to be attached.
(You will probably understand this after you have read my narrative.)
I used my band saw to make this
cut. I attached a fence for a guide because I wanted my blade to be just
inside the interior wall of the piece and cut straight. The cut is length
wise up to the mark, remove, and cut across at the mark so that you have that
section removed.
This is a chamber support.
Keep the pieces cut away, we will use them later.
Next, cut a piece of ½ inch PVC
pipe about 2 ½ inches long. This piece is used to join two of the (slip)
T’s. Dry fit the short piece of pipe into the
ends of two T’s to make a single unit, and insure that you have about ¾ to 1
inch between the T’s. It will be critical that the two T’s
are aligned properly before gluing. This glue sets in about 10
seconds, so dry fit and
mark alignment on each piece each time
from here until fully assembled and finished before any glue is applied. Here
you might use the two chamber support pieces and dry fit them in the center
hole of each "T". Insure they are in perfect alignment with each
other. Then with a felt tip pin you can
mark on the white PVC T's and short piece of pipe joining them. This will insure that after the glue is
applied and you push the pieces together, then these marks will guide you. Just be sure the short piece of pipe joining
them does not get reversed. When
applying the glue, use the ‘applicator top’ of the can and swab glue in the
opening of the T that will receive, as well as the end of the piece going into
that T. Once glued &
aligned properly, you should dry fit the two chamber support pieces
and be
sure they are in alignment. The chamber
supports are not glued yet because they must be finely tuned in
order to get the correct position for attachment to the bubble chamber. This means that you should turn them
so that the cut away area now may be in full contact with the outside of the 4
inch bubble chamber.
Now mark the T’s and supports where
they join, and draw the outline of the supports onto the outer wall of the
bubble chamber so you will know where to put glue. A special
consideration has to be made at this point. The top of the chamber will have the
reducer added. Dry fit the reducer top on the chamber and see if the outer lip goes
below the mark that is the top of the support. You may need to shorten
the supports.
Remove one support from the T, add glue, and replace it being
very careful to align the support with the marks for that T and let the glue
set. Follow this with the other support and this time, check the
alignment by holding the bubble chamber against the two supports to see if any
adjustment is needed, then give that a minute to set.
Next apply generous glue to the
supports face that will contact the chamber and a generous amount to the
chamber within the lines that show where the supports will mate.
Clamp this and give it about an
hour to set and dry. If you are successful in the alignment you will be
able to see that the chamber has not only made contact with the supports where
you cut away part of the pipe,
but it will sit on the notched
part just above the T’s. Once this has dried you should take the two
pieces that were cut from the chamber supports and glue those for additional
strength and reinforcement to the supports.
This is not necessary, but may
extend the life of your filter by preventing detachment.
Now cut two pieces of ½ inch pipe
1 1/2 inches long, longer if you want a wider base. These are used to
attach the two (slip) T’s that will accept the feet.
This is where you will decide if
your filter is to sit on a flat bottom or a slant. Once the dry fit is
accomplished and you position them, then mark and glue them. I will refer
to one side as the ‘outside’ and the other as the ‘air approach side’. From the ½ inch pipe, cut two (2) pieces 9 1/2 inches and one (1) 5 ½ inches.
These are glued into the T’s with the (2) 9 ½ inches on the back side of the
chamber where the supports are, and the 5 ½ inch is on the front of the
‘outside’ T. Next is the front foot for the air approach side (here it is
the front right section assembly).
Turn the unit upside down and dry
fit a (slip) T and a piece of ½ inch pipe about 2 inches long. Adjust the
length of the piece of pipe until the center exit of the T is in alignment with
the center of the air chamber. Mark the alignment so that the center exit
of the T is in the same plane as the T it is joining, and glue.
Next you will need the elbow and
a piece of the ½ inch pipe about 3 ½ inches long so you may adjust length and
dry fit to position.
The elbow
and short piece of pipe are fitted into the center exit of that last T that you just added.
By
adjusting the length of the pipe joining the elbow and the T you will move the
elbow to a position that is approximately center of the air chamber. The
dry fit of the elbow can be better aligned if you use a long piece of the ½
inch pipe as a guide (but do not glue this one) through the center of the air
chamber. Once this is accomplished you should mark and then glue the
elbow into position. This is also a good time to add ½ inch pipe that
goes into the end of the T and completes the front part of the foot on the ‘air
approach side’ (bottom left of photo). Glue it first and then measure it
against the other foot to see where to make your cut.
Take one of the ½ inch PVC plugs
and sand, or cut, the ears of the hex head so that the plug is rounded on the
head and will fit into the elbow. Mark half way on the plug and glue it
into one of the slip end of the last T that has the threads in the inside of
the center hole. Make sure to leave half
of the plug sticking out of the end. This is the
"air attachment unit". Those threads in the center exit are so the air attachment can be screwed into it.
Now get the two adapters, about 2
inches of pipe, and the other plug. The
plug is to be glued into the slip end of the adapter with the threads on the
outside. When they are dry fitted, there
should be about 1/4 inch of the plug shaft showing between the hex top
and the mouth of the slip end of the adapter. In that area you will drill two 5/64
inch holes slightly angled down on opposite sides after the glue sets. After you have the system working, you might
add more holes or larger ones depending on the power of your pump. This is ready to glue. Next screw these two pieces into the mating
end of the other adapter with the threads on the inside but do not
tighten. Let the glue dry for about an hour, then drill the 2 holes and add the short
piece of pipe.
This is the "bubbler".
Dry fit the bubbler into the top
of the air attachment unit. As soon as you have the two together, please
blow into the T’s center hole and be sure that the bubbler allows the
air to flow out the drilled holes and the plug in the bottom prohibits. Then fit the air attachment unit with the
bubbler into the elbow. You want the top
of the bubbler, which is the top of the hex head plug, to be positioned such
that the 2 holes will be about half way up the inside of the 4 inch
chamber. If not then remove the assembly
and adjust the length of the 1/2 inch pipe to correct. When this is all correct, you should glue the
pipe into the bottom of the bubbler. Now
glue the bubbler into the top of the air attachment unit.
Now glue the air attachment unit with
the bubbler into the elbow and be sure that the center hole of the T
faces to the side. This is where the air hose will be connected.
The bubble chamber should be
about like this photo at this point. Measure
the distance from outside of one foot to outside the other and cut 2 pieces of
the ½ inch pipe just about an inch longer (mine were about 10 inches long).
These new pieces are to be
notched to lie across and on top of the longer two feet in the back of the
chamber, and will support the brick that will be the ballast. These two
should be positioned perpendicular to the two longer feet behind the chamber
and marked for the circular notches to be cut. This is the hardest part
since they need to make good contact. Cut away some and check the fit,
then shave some as you adjust. When you get one right, then put the brick
on the feet and let the first notched piece go between the chamber and the
brick, then glue and clamp that one. Now cut, adjust, glue, and clamp the
other one.
While that glue sets you can glue
the 2 inch reducer on the top of the 4 inch air chamber. Then the 2
inch PVC pipe glues into the top of the reducer, and the 2 inch couple glues
onto the top of the 2 inch pipe. Again dry fit and remember that another
12 inches will be on top of that when the filter bag is attached, wet, and
inflated by air and the flow of water upward.
If needed, you can adjust the length of the 2 inch pipe that is the chimney on top of the reducer.
After placing the brick on the feet,
I realized that the brick is just barely short enough that it might slip off
the support. So I cut a 6 inches piece of ½ inch pipe and used my band
saw to cut it in half from end to end.
Turn the unit on its side and
glue these two pieces in a position that will further support and stabilize the
brick.
Now the brick should stay in the
desired position.
Notch the brick at the midpoint of each end on top as a guide for the strap that will hold it on the assembly.
I used plastic zip ties that can be purchased many places for
my strap. Mine were too short so I put them into each other until they
were long enough to go around the brick.
Zip it tight and cut the extra
off.
The 2 inch couple on top of the
chimney will prevent the bag (filter) from sliding off the top.
The air hose is attached using a
piece designed for lawn sprinkler systems. The air hose slips over one
end and the other end screws into the threaded opening of the T. There is
no reason to glue this piece, just tighten by hand.
The filter is made from one
of those mosquito nets that you can purchase from your local Army
Surplus or Military Surplus stores (or you can find one on the internet).
It is made to be supported at each end and drapes over a metal cot, as in
Army barracks beds. I'm just guessing that it is about 6
1/2' long, 3' wide, and 4' tall, it kinda makes a box to cover a bed so a
person can get away from mosquitoes.
I took one and cut along
the seams to get it into flat pieces, then cut a long strip about 14 inches wide.
From this strip I cut pieces about 2 ft. long, fold it over to be about
12 x 14 and sew, with my sewing machine, the two outside edges which makes a
bag almost square. Now fold the open end back like a hem of 1 inches and
sew it around leaving about 1/2 inch from the folded edge.
Next I used
a needle and some 2 pound fishing line to sew everywhere I had sewn
with the sewing machine. Just to get the most for my effort, I did sew
twice with the fishing line. The reason for this is that
the sewing thread will deteriorate after
about 3 or 4 uses of the filter. With the reinforcement that the
fishing line adds you will get to reuse these bags for a very long time (mine
are in their third year). Turn the bag inside out, snip the edge to
make a cut about 1/4 inch, and
I slide a 14 inch Zip Tie into
the path to go around the bag and out that same hole again. The bag will
be gathered at spots so even it out and then slip it over the 2 inch
couple, making sure that it goes below the couple and zip the tie so that it
tightens to the 2 inch pipe of the lesser diameter.
Here I used a white net bag and red string so you could see how it will look.
These will last depending on leaves, grasses, algae, and such that gets filtered out of the water from the bubbles flowing up the air chamber with the chimney on top. The indicator will be the air bubbles that you see on the surface of the pond. Mine last about 3 months, and when I change them, I save the old ones. I wash them under a faucet, scrub the material against itself and do some cleaning by hand, but no soap. I hang them in a sunny place to dry out and if needed later I'll use a medium stiff brush for the final cleaning. They are reusable to the point that since I started using them over 3 years ago I have not had to replace any.
Above is my personal effort and
the bags in the picture are not the right ones. These are first ones and
they did not do the job. After I tested the first unit I made, I
concluded that the pond would get back to clear, and pretty, twice as fast with
two filters, so I made another and fitted them as shown.
One concern is a law of
physics. Air (like water) will flow to the path of least
resistance. When I used only one filter, it bubbled like crazy and I felt
it was really doing its job. Then I made another filter and added it to
the system. When I first slid the two down into the pond, I could only
get one of the filters to bubble. As I repositioned the unit by gently
moving one higher than the other, I was able to get the other one to bubble,
but the first one stopped bubbling. I thought this is probably a result
of one bubbler having more holes than the other, or holes in one bubbler might
be larger than the other one.
I kept checking on the system for
about a 2 week period, and found that finally the air pressure in the assembly
sort of equalized and as time passed the other filter began to gain
momentum. After being patient and giving it some time, the two filters
are currently bubbling about the same amount, and I can live with that.
I took a piece of 1/8 inch nylon
twisted rope about 20 feet long and tied one end to the brick on one of the
filters and then the end to the other brick.
This is used to pull the filters up out of the pond for cleaning. Then I made a small bug proof house with vents
on each end and an aluminum sheet over the top for the pump.
You could use a 2 inch air
chamber with a 1 inch chimney if your pond is not 4 feet deep. There are
many adaptations, combinations, and permutations that could allow you to
customize this filter to your particular situation.
After I finished the
filter and put it in my pond, I realized that at some time in the future I will
have to be able to unscrew the top piece of the bubbler that was inside the 4
inch chamber. The only access I had was
down through the 2 inch chimney.
So, I took one of the
hex head plugs and made a trip to a local pawn shop. I found that they have a wealth of metal
sockets usually in a large box for customers to dig through and find what they
need.
I found that a 24 mm
socket would fit on the hex head plug, and I think it was only a couple of
dollars.
I took this home and
found an old yard tool handle that had been broken, so I cut the splintered
part off and that left an excellent handle for this new tool. The first inch after the cut was used to cut
into a square tenon that would fit into the drive hole for the socket.
Then I drilled a hole
for a dry wall screw in the center of that tenon.
Next, I got a slug
like the ones you punch out of a metal 4 inch square box mounted in the ceiling
for a light fixture to be mounted onto in a home. I drilled the center of that slug with a hole
slightly larger than the one in the tenon.
Just a little
grinding on the slug and it fit down inside the 24 mm socket.
Now I have a
specialty wrench for removing and reinstalling the bubbler for cleaning when I
replace the filter bags.
I also found a 5/64
inch old broken drill bit, so I mounted about a 1 inch piece of 1/4 inch dowel, with a hole drilled in the center, onto the broken bit for another tool to use for cleaning out the
holes in the top of the bubbler.
And finally, an old
tooth brush that will go up into the inside of the removed part of the bubbler
to ensure that the inside is scrubbed out also.
After about a year in the pond the white PVC will be mostly black
because of the algae growing on the surface.
This also gets inside the bubbler and will affect the air flow.
UPDATE, JUNE 2020:
Thanks for looking
and good luck, I hope this will help.
UPDATE, JUNE 2020:
After a few years of cleaning the bags and the
top of the bubbler, I found that I spend too much time trying to get the two
bubblers to stay bubbling. I get the two
working just fine, then a couple of days I check and only one is bubbling. I thought a long time trying to figure how to
correct this. I pull the small rope
attached to the one that is not bubbling, which raises it slightly, and it
starts to bubble. A day goes by and I check
it again and the other one is not bubbling.
I came to this conclusion:
1. The size of holes drilled must be the same for
both.
2. The number of holes must be the same for both.
3. The air will follow the least amount of
restriction
The least amount of restriction means that the
two units must be at the same depth in the pond, or the air will flow to the
one that is higher than the other one.
Considering the small amount of flexibility in the PVC pipe and the inability
to control the mud bottom of the pond from being unlevel, I decided to cut 8
inches from the distance between each bubbler stack and the connection from the
air hose. This moved the two stacks 16
inches closer together and will probably get them closer to being on the same
plane at the bottom of the pond.
Then I considered the depth of the pond and the
volume of water will be a major factor in the amount of force that the air pump
will have to overcome to get air down to the stacks. This made me reconsider the number of holes
in each bubbler head. I took a tooth
pick, jammed it into one hole in the bubbler head and broke it off, then to the
opposite side of the same head and plugged the opposing hole there with the
same tooth pick. The wood will stay if
it is tight because once in the water it will swell somewhat and that should ensure
the hole remains plugged. I did the same
thing to the other bubbler head in the second stack. These two changes in the system have made a very
good adjustment in getting the two bubbler stacks to produce near equal air
flow. If I have any problem in the future,
I will plug another hole in each bubbler head, and if necessary, I can still
move the two stacks closer and plug another hole in the heads.
I have added these changes to my article because
you might have the same problems if you decide to make this system, and I want
to share that the depth and volume of your pond, as well as the size and number
on holes you drill in the bubbler heads, and the distance between the two
stacks, will be the major variables to the success of your efforts. The nice thing about this system is that it
will ensure an adequate flow of air into the pond for your fish and
plants.
Now if I can only find a treatment for the
algae and a good clarifier for the water.
If I do, I will definitely have another addition to this article.
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