CO2 - the basics
What is CO2?
CO2 is a gas that is present in the atmosphere that is essential for plant growth. Plants take it up through holes in the underside of the leaves called stomata.
Why is CO2 important?
During the light period, plants convert CO2 in the atmosphere into carbohydrates. This is called photosynthesis. Plants use the energy from the sun (or your lights) to split the CO2 into carbon and oxygen. The carbon combines with water to become sugar. By weight, dried plant tissue is more than 50% carbon - in this way you can think of CO2 as a fertiliser you add to the air!
CO2 levels in a grow room where additional CO2 is not being used can often become depleted, because fast growing plants are using it up at a fast pace. This can cause growth to slow down.
What is the ideal CO2 level?
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We recommend you shouldn’t have more than around 1500ppm (parts per million) of CO2 in your plant’s surrounding atmosphere. Levels above 2000ppm can damage the plants, by stunting the growth. You must remember normal atmospheric CO2 levels are only around 350ppm, so this is what most plants will be “used to”.
How do I know how much CO2 is in my grow area?
To measure the amount of CO2 in your growroom you need a CO2 test kit. This consists of...
• Tubing
• Syringe 100ml
• CO2 test tubes
CO2 is measured by pulling air through the tube and matching it to a colour on the chart provided, similar to pH testing. The tubes can only be used once but the syringe and tubing can be reused as many times as required. The tubes can also be bought separately.
A more advanced way of checking how much CO2 is in your room would be to use a CO2 analyser. This constantly monitors the levels of CO2 in your grow area, and is an add-on to your CO2 controller, so should really be used in conjunction with adding CO2 into your room. Readout is in ppm so allows you to know whether to increase or decrease the CO2 levels that you are already adding to your room.
How to know if CO2 is right for your grow room...
Adding CO2 to your growroom will only increase your yields if all other variables (e.g. temperature, humidity) are within the correct range.
This is because CO2 allows your plants to grow much faster, but that means any deficiencies will show up faster too. A healthy plant will be able to use the added CO2; a nutrient deficient or diseased plant will not. Therefore we would recommend that CO2 is one of the last additions to your setup. If you are exchanging the air in your room at a high rate, CO2 enrichment is likely to be difficult to achieve. If you do add CO2 to your growroom you will find your plants can tolerate higher light levels and higher temperatures, so less ventilation is necessary, provided your humidity levels are controlled.
How do I get the most out of my CO2?
As plants only use CO2 when they are photosynthesising (i.e. in the light) it is pointless to enrich the environment with CO2 when the lights are off. For the best effect, timers should be used to ensure the fans are turned off while the CO2 is being released, to maximise the chance of the plant being able to uptake as much CO2 as possible. If CO2 gas is being released through CO2 tubing or other methods, remember CO2 is heavier than air, so place the release point as high in the room as possible. CO2 will be produced by plants in the dark, but at this time it is not used. This means CO2 levels can be quite high at the time when the lights just come on, so you do not need to switch on your CO2 until about an hour after the lights come on.
Safety using CO2
If CO2 is being provided by a gas burner: make sure that nothing is covering the equipment. This allows CO2 to escape with ease, but more importantly reduces the risk of fire. Gas burners can produce the deadly gas carbon monoxide. The presence of this gas can be detected by cheap card sensors that change colour in its presence. These are available from many hardware stores or online. As carbon monoxide is colourless + odourless it is well worth investing in one of the sensors if a gas burner is being used.
Electrical equipment: Make sure that all the wiring on electrical equipment is not damaged as electricity and water in your grow room is never a good combination.
CO2 test tubes: Be careful with the broken glass on the CO2 test tubes and dispose of the used tubes in a safe place out of reach of pets and children.
CO2 bottles: If using gas bottles, make sure there is a protective collar on top to shield the valve (on all bottles provided by us.) The pressure inside the bottle is enough to send the valve regulator etc through a wall if the valve is accidently knocked off, so handle the bottles with care at all times.
Which CO2 system should I use?
CO2 emitter system (bottle + gas kit)
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These systems do not produce toxic gases, heat or water as a by-product of your CO2 release
(unlike other models such as the gas burners). You simply pay a deposit on your first bottle, return
it to us when it is empty and we will swap it for a full one, where you just pay for the CO2 inside.
You get your deposit back whenever you want to return your bottle for good.
CO2 bottles are only available for collection. Please visit our Manchester or Burnley branches
to buy this product. We cannot send CO2 bottles by courier because of the safety issues with
pressurised gas.
(PICTURED: CO2 BOTTLE DEPOSIT, XKHS2238, £30 - REFUNDED UPON RETURN WITH VALID RECEIPT, AND CO2
REFILL, NXY5335, £10.25)
To use this setup you need a gas bottle, regulator, controller and CO2
tubing. For more information on our CO2 regulators and controllers, speak
to one of our members of staff, who will tell you all you need to know about
this setup.
(PICTURED: UNIS CO2 CONTROLLER COMPLETE, RXG9722, £168.55)
Gas Burners
These release CO2 from burning propane gas. It will also heat up the growroom so
is a good option for fast growing tropical plants or use in winter. However, heating is
kept to a minimum by short burn times.
(PICTURED: GROWTH GAS GENERATOR, FAE8173, £280.90)
CO2 Boost
This product uses microbial culture to provide CO2. It is suitable for smaller rooms
and perfect for the 1.2m tents. Once activated it must be used immediately and
will provide CO2 for up to 90 days. This is a product with a dual purpose as once
the contents of the bucket have been activated for 90 days and are no longer
producing CO2 it can be used as an organic fertiliser for soil. Refills are available to
add to the bucket.
(PICTURED: CO2 BOOST KIT, FZZ3633, £122.60)
Excellofizz CO2 Tablets
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This is another product perfect for the smaller growroom. It has no need for dispensing
equipment, just add water to the bucket the tablets come in, place the bucket as high
as you possibly can in your room, add a tablet and you are set to go.Excellofizz also
contains eucalyptus which gives a fresh fragrance to your grow room, as well as helping
to repel pests. There are 15 tablets in each pack.
No Mercy CO2 Tabs
These are solid tablets that are added directly to your nutrient tank, for CO2 uptake
through the roots of your plants whilst also rising up through the water. There are 60
tablets in a pack.
(PICTURED: NO MERCY CO2 TABLETS X 60, JWR4538, £18.95)
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