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Controlling Grow Room Odors
Ideally, use a 2-prong approach for the best results. This entails
running an ozone generator and an exhaust fan with a carbon filter.
EXHAUST FAN AND CARBON FILTER:
You can run
carbon filters in a couple of different ways.
1.
First, is pre-exhaust where you need to exhaust heat (and / or
humidity) from the grow room. In this setup, the carbon filter goes
into the grow room, where air is drawn first through the filter,
then exhausted out of the room. The size of the filter has to be
matched to the size of the fan so that the air going through the
filter has enough contact time with the carbon to do it's thing. If
you pump the air through the filter too fast, the carbon can't do
it's job. So, depending on how much heat you've got to remove,
you first determine the necessary fan size, then pick the correct
filter for the fan. With the right fan/filter combo, all of the
air being exhausted will be clean enough of organic fertilizer odors
to blow directly outside (or into your house in the winter to
utilize the heat and high quality oxygen rich air).
2. The other way to run a carbon filter is to simply connect
the fan to the filter and put it into the area that you're concerned
about with no ducting. This is called "polishing" the air and a
larger fan with more air movement can be used because the air is
being repeatedly drawn through the carbon filter. With this
approach, the larger the filter and fan you choose the better.
Overkill is
a good thing!
CFM (cubic foot
per minute) FOR AIR MOVEMENT:
The air
movement (or CFM) isn't the only important part in matching the fan
to the filter. It's also the 'pressure' of the fan's output. If you
were to run a squirrel-cage type fan on a carbon filter (or an
in-line duct fan, or an axial computer fan), they won't have the
same torque as a centrifugal fan, so the CFMs aren't the same when
you restrict the air movement with the carbon filter. It's hard to
get a good match between different types of fans with the carbon
filters but it can be done. It's just kind of a hit/miss approach to
find the correct air movement with a fan other than the sizes that
the manufacturers recommend.
As for the air movement, you can push or pull through the filter,
and it will work just as good either way, but in the long run you
want to pre-filter the air to get all of the dust out before the air
enters the carbon filter. The CAN filters come with a white poly
outer pre-filter to remove all of the dust before it can create dust
pockets in the carbon. If the dust is allowed to enter the filter
(without the use of a pre-filter), it creates pockets of dust that
promote bacterial growth, and this bacterial growth limits the
overall life of the carbon. So, a pre-filter is important either
way whether you push or pull through the filter.
OZONE GENERATORS:
Ozone use for
odor control has a long list of pros and con's, but one of the good
things is that it kills bacteria, not only in the growroom,
but in the exhaust fan and carbon filter. So, if you've got an ozone
generator treating the air in the room before it enters the carbon
filter, it will kill the bacteria that can limit the life of the
carbon.
This dual
approach, using ozone and carbon (filter) to deal with your organic
fertilizer odor issues is probably the best overall approach if
money isn't an issue.
Here's a list of some ozone pros:
Kills
bacteria.
Removes all odors from the air very effectively.
Creates an environment that spider-mites don't like (it won't
get rid of a problem, but it will help keep spider-mites from
getting out of control).
Controls mold and powdery mildew both on plants and in the room.
Here's some
con's:
It's so
effective at removing odors it can affect the flavor of your
produce, or the aroma of flowers.
Supposedly it's not healthy for our lungs to be exposed to ozone
for prolonged periods of time.
Ozone has a
half-life of about 15 minutes, meaning that if you plug an ozone
generator into a timer that runs the generator 15 minutes on / then
15 minutes off, you've still got 100% ozone enriched air. I'd
recommend taking this timer approach to ozone, running it for as
little as possible. This way, you've got minimal effect on your
plants, and your lungs.
POLISHING:
Air polishing lets you clean the air
without chemicals or outside venting. Learn more about it
here.
