In this, the last installment of
Dr. Goodbud, the kind doctor
imparts the basics of
C02 FOR THC
The 3 Goals of Good Ventilation
- Provide a rich carbon dioxide environment for your cannabis plants to promote optimum growth.
- Eliminate the smell of marijuana that will otherwise permeate your grow area, home, and spread into public areas.
- Keep the grow area dry, thereby reducing mold on flowers and walls, and retarding algae on soil and in overflow tray.
Maximum Growth and Vitality
Carbon dioxide is the lifeblood of your plants. They absorb carbon dioxide, and use sunlight to break it down into carbon and oxygen.
The carbon is used to build plant structure, and the oxygen is released as a by-product.
For maximum growth and vitality, you must provide your plant with optimum levels of carbon dioxide.
Most problems associated with growing indoor marijuana are ventilation or carbon dioxide related.
Mold on the plants, algae on the soil, yellowing of the leaves,
stunted growth, withering, death of the plant, and smells that get out to hostile nostrils are all usually ventilation and carbon dioxide related problems.
If you do not provide large quantities of fresh carbon dioxide then your plant will suffer.
You must therefore add carbon dioxide directly into your environment
through a supplement (compressed air tank, propane burner, etc.), or you must br
ing in a constant flow of fresh air from outside into your grow area.
As the plant mass becomes larger, it needs more carbon dioxide. A marijuana plant at four
months requires at least twenty times more carbon dioxide than a tiny seedling.
The individual cells do not use it any quicker, but there is an exponential advance
in the total number of plant cells.
Whump, it turns Yellow
What happens if you don’t properly supply the carbon dioxide your plant requires?
It dies, but it’ll tease you first. It will get to a certain height and then. . . whump,
it turns yellow, withers, and bends over. You’re starving it slowly with inadequate carbon
dioxide. You try changing fertilizers, you water it more, but it withers, and you’re
extremely frustrated. Ventilation that was adequate at 6 weeks is not adequate at 5 months,
the peak of the bud cycle.
The Working Model
The first two installments in this series explained your requirements for soil and
lighting. Our working model is four to ten plants in a 10′ x 10′ x 10′ indoor room.
The plants are in 15 gallon soil containers, with Black Gold All-Purpose soil or
Peter’s Professional potting soil, mixed 3:1 with vermiculite or perlite to promote easy
and rapid root extension. One tablespoon of Alaskan Fish Formula added to every
gallon of water is a suitable fertilizer at the grow stage.
Our lighting system during the grow stage is two (ideally four) 1000 watt metal halides.
When you cut back to twelve hours for the bud cycle, you should add one or two HPS lamps of
1000 watts each. Ideally you’d replace all metal halides with HPS bulbs, and ad
d 50% more wattage to keep power consumption the same.So, for our indoor grow operation,
we have a sealed, well lit, mylarred room, which has been bombed with insecticide before
any plants are brought into the room. (It may be environmentally unfriendly, but it has to be done.)
All containers for soil should be washed thoroughly in very hot water, but without using bleach
or anything else that could leave toxins. Now you are prepped and ready for Dr. Bud’s Growline
on ventilation and carbon dioxide.
The High Rise Ideal
If you can work it out, the ideal setup would be to live in a high-rise with a big
open window and a regular ocean breeze coming in. All ventilation considerations are
met due to the constant fresh carbon dioxide with mild drying breezes.
There is little chance of spider-mite, whitefly, or aphid infestation if your grow room
is sprayed with insecticides beforehand.
This could be perfect in its simplicity, but is it practical for you? Police busts on
private property for four to ten plants almost never happen these days. Almost every
high-rise in the West End of Vancouver, for example, has plants on balconies or by windows,
particularly the southern exposures facing English Bay.
At ground level, however, leaving a window open during the day with a plant in view is an
invitation to get discovered by nosy neighbours, or even to be ripped off by marijuana poachers.
A Wealth of Carbon Dioxide
You need 3 to 5 times more carbon dioxide in your grow room than is found outdoors.
In nature, there are 300 (country) to 400 (city) carbon dioxide parts per million,
but for optimum plant growth in controlled circumstances you want about 1500 carbon
dioxide parts per million. For this you need additional supplements of carbon dioxide.
Circulating air, even fresh air, or fanning the plant, does not increase the
amount of carbon dioxide available for the plant. At best this will provide a
constant 300-400 carbon dioxide parts per million.
Get a carbon dioxide system going.
It is not complex or elaborate. You could go buy a canister outright. Do not use credit cards,
but do use the universal green collar code word “tomatoes” when discussing your gardening.
Alternatively, if you know who works at or owns a restaurant where there are soda drinks,
the carbonation is done by compressed carbon dioxide added to the liquid. They get their carbon
dioxide canisters delivered.
Or just find out who fills up all those carbon dioxide containers and get it from the source.
Call a restaurant equipment and supply company in your Yellow Pages.
A 50 pound tank of compressed carbon dioxide should last you about two or three weeks,
and will cost about $300. You can get it refilled for $40. A regulator, which controls
the release of carbon dioxide, is $250.
If you go with a carbon dioxide tank system as suggested above, your grow
room has to be sealed so you have greater control of your grow environment.
Ideally, you should go automated, with a timer on your tank and lights. The exhaust
fan should be on much less however, because you would be throwing out your carbon
dioxide enriched air. It is recommended you get your exhaust fan in sync with
your carbon dioxide timer.
Without a carbon dioxide system, you must draw air in from the outside to maintain a
constant level of new carbon dioxide. For this you need a strong squirrel cage fan and vent system. Simply put,
this will bring air in and send it out. If your room is 10′ x 10′ x 10′ (1000 cubic
feet of space) then you want to be able to move approximately 1000 cubic feet
of air per minute (1000 CFM). A 985 CFM Dayton squirrel cage fan is about $300,
and it needs a four to eight inch exhaust hole in your outer wall.
When deciding on a squirrel cage fan system, calculate the volume of your room
(width x length x height). A 12′ x 15′ x 8′ room needs 1440 CFM air circulation.
The Dayton dealer can help you with vents and ventilation advice because they deal
with greenhouse operations.
Maybe Not a Great Idea
Another method to produce carbon dioxide would be to have a propane burner on 24 hours a day,
the by-product of the flame being carbon dioxide. This can work, but you do run the serious
risk of burning down your house. If you decide to use this technique, please be very careful.
If you’ve got a good strain, those plants are going to stink, and you’ve
got to get rid of that pungent marijuana smell.
You’re going to need an odour filtration system. For our 10′ x 10′ x 10′ room with 1000 CFM air flow,
(less if you’ve got a carbon dioxide system) the exhaust is carrying a pungent odour
with it, a major security breach.
For this serious concern, buy an air filtration system. Many people make the mistake of getting a
small $200 negative ion generator. The theory is that it “weights” the smelly molecules and this keeps them
at ground level where there are not human nostrils.
Although a small generator might work for one plant in a closet,
what we want is something that will clean out the smell of 1000 cubic feet per minute,
60,000 cubic feet per hour.
I recommend you buy a commercial heavy duty air filtration system, the kind you’d find
in a restaurant to eliminate heavy cooking-oil smells. This kind of unit is adaptable
to almost any room. Check out restaurant supply outfits for availability.
A commercial sized negative ion generator is only about four cubic feet, and it
can be anywhere in your grow room as long as the exhaust is channeled outside.
The filtration unit’s exhaust hose would be in your duct work between the
squirrel cage exhaust fan and the outside vent.
The filtration unit’s exhaust hose would be in your duct work between the squirrel
cage exhaust fan and the outside vent. This is the safest place to send the exhaust:
between fan and exhaust port. This way there will be no hazardous side-effects to your health.
An improperly regulated heavy duty filtration unit inside your home can adversely affect
Big Money, Big Prizes
A good heavy-duty air filtration unit costs over $1000, but remember that four
plants can be worth $30,000 within six to seven months, so all your initial startup
costs are covered in the first small harvest.
If you are thinking “Whoa! Way too much money!” then think again. Investing in the
right security and the right equipment will return five to ten times the value of
your investment in the first yield. After this, when all your equipment is paid
for, the potential financial rewards are fantastic. Conversly, you can spend your money
on legal fees and fines and have no grow operation because you wanted to cut corners.
A heavy duty air filtration system is a cheap insurance policy against the wrong noses
getting ideas. A good unit totally cleans all odours from your operation.
Your marijuana plants, at maturity, have a value of up to $7,000 per plant (36 ounces of bud)
if you follow our seven month full-cycle grow method as outlined in these three articles.
You must consider investing some serious money in your overall growing plans, per
haps $3000 to $5000 for your first harvest. This should yield you fine marijuana
of an astounding value in only six months. Invest the money!
Low budget filtration ideas. . .
a. Mothball Cage
No Money? No Problem!
If you don’t want to go with this method, then disguising the smell is your next
best option. You could send your exhaust air through a mothball filter of your own
construction. Calculate the dimensions of your exhaust duct work, and build a frame
about four inches thick, filled with mothballs. The pungent marijuana odour will be
distorted by the pungent smell of the mothballs, so it will not be recognizable when
the air emerges from your chimney or into the back yard.
b. pinesol barrel
Alternately, you could send the air through a fifty-gallon barrel of pine sol, a very
powerful disinfectant that will mask the smell. When the exhaust air flow is funneled
into a tube and into the barrel containing pine sol, it is so strong that it bubbles out into the
liquid, masking the smell. To prevent the reverse flow of liquid into your
duct system, the top level of liquid pine sol should be below the level of the
Noticeable humidity in your room is not healthy. It means you have inadequate air flow.
Try putting a dehumidifier where your air comes in, and this way you take moisture
out of the air as it enters your grow room.
A desert-like situation is best for marijuana, because then the plant wants more water through its
root system, meaning more growth. Humidity means it will do the opposite: draw only
small portions of water while struggling to breathe from a lack of fresh carbon dioxide.
All mold, algae, spider-mite, aphid, whitefly, and fertilizer problems are reduced
with proper ventilation.
The best marijuana strains come from mountainous areas with good soil and lots of hot sun,
with strong ocean breezes to modify the effects of humidity, and a daytime temperature
of 25-30 degrees celsius, and nighttime temperatures of 18-24 degrees.
This is the environment you want to simulate.
Good luck and good growing! This is the conclusion of Dr Goodbud’s