| A venturi functions just like a carburetor. A
venturi compresses the flow of water then abruptly releases it into
a larger chamber which creates a vacuum. If a source of air is
present at the point of release, air is sucked into the stream of
water creating the bubble effect at the end of the pipe.
A homemade venturi is not to hard to make out of PVC pipe
fittings. The key is the nozzle which is inserted inside the
pressurized return line just at the junction of a tee fitting.
The nozzle should reduce the inside diameter of the pipe by around
50%. Try to have your "tee" fitting near the waterline, the
deeper you go, the more pressure you'll need and less air will be
sucked in. Experiment before you glue things together!
In fact try not to glue anything aside from the nozzle so that
you can make future adjustments and cleaning. (If your are
setting this up outside your pond then you will obviously need to
glue everything together to prevent leaks)
 | You'll need to cut, sand, and shape the PVC parts that make up
the nozzle to get them to fit together but other than that is a
pretty easy project. |
| Take a look at my
schematic and
the images above to get a good idea how to make your own venturi. |
Unfortunately venturi's can be loud, especially when you use
smaller diameter tubing. This really does ruin the serenity of your
water garden. I made a
muffler to fix this problem with an old spice jar and some
scrap filter material jammed inside. Just
drill a few holes in the spice jar lid, one for the air pipe and
several smaller ones to let the air in. Then spray paint the
whole thing to camouflage it.
Click here
to listen to the difference.
*Several websites I have looked at recommend using a brass natural
gas fitting or copper tubing as a nozzle. I recommend you not
do this as the brass and copper will leach unwanted chemicals into
your ponds ecosystem. My nozzle is made out of PVC type
plastic which is all rated for potable (drinking) water and won't harm any pond
life.
Why aerate your pond water?
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Aeration
improves water quality by maintaining good dissolved oxygen levels
in the water especially where oxygen is really needed -at the
bottom. |
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Aeration reduces algae growth by
removing its food (nutrients), Nitrogen, ammonia, and soluble
phosphates are driven into the surface air and out of the
pond. Iron and manganese are oxidized and drop out of solution
to the bottom of the pond. Once oxidation of these metals
begin, they don't go back into solution. Aeration increases
aerobic bacteria which eat the other nutrients on which algae
and weeds need to grow. The aerobic bacteria eat these
nutrients before the weeds and the algae can... Forcing it to
starve and die. |
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Aerobic bacteria are the good guys: They
breathe oxygen and exhale CO2 like us. They have a huge
appetite eating anything organic very quickly. The aerobic
bacteria begin to eat the organic sediment at the bottom of
the pond and will continue to eat it as long as they are given
oxygen. |
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Aeration also works for
de-icing a winter pond. Moving water won't freeze so an
opening remains ice free above the bubbler. |
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Check out these sites as well: |
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Garden Endeavors: how to make a venturi |
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Venturi Pond Aerator - Improve your pond's ecosystem by a
Venturi aerator |
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How To Build The Venturi |
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PVC -the stuff filters
are made of |
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