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MASTERING ENVIRONMENT CONTROL

The most important element to get right in a growing area/room is the environment. Mastering the environment will help to achieve the maximum potential yield from the plants. Bringing in clean, fresh CO2 rich air into the grow room while extracting stale, CO2 depleted air out.

In setting up the grow room/tent you need to consider:

  • Air intake and extraction
  • Air circulation
  • Air temperature
  • Humidity

You will find advice and guidence for each of these in the product categories.

Extraction Fans and Kits

There are 3 ways to setup air exchange

  • No re-circulating air intake fan - air extractor fan
  • Oscillating recirculating using fans and an air intake and extractor
  • Diffuse air product and extractor.

A general rule is to always over specify your fans. Don't buy the minimum you need as you will have no spare capacity should you change the setup of your room.

To work out the size of your fans you should aim to exchange the air in your room once every minute. To do that you need to work out the volume of air you need to move per hour. Our fans are rated in m3/h so this is the figure you need to calculate.

First work out the volume of your grow area by multiplying the length x width x height of the space. For example take a tent 2.4m x 2.4m x 2m = 11.52m cubed. Multiply this number by 60 to get the volume of air you want to move each minute  11.52 x 60 = 691.2m cubed / hour.

You next need to consider the heat the lights will produce. As a general guide for every 2 watts of light energy added to the growing area you need to extract 1m cubed/hour of hot air. Our current calculation 691.2m cubed x 2 watts = 1382.4 kilowatts or just over 2x600w lights. For this size of growing area we would normally use at least 4x600w lights.

So we would actually need a fan with a minimum metre cubed / hour 

4 (the number of lights) x 600 (watts) x 0.5 (as its 2 watts per m3/hour) = 1200 m3/h size of fan we would need.

If we added a 1000w lamp in the middle as an extra light source we would need to add 1000w x 0.5 = 500m3/h extra capacity so 

1200 + 500 = 1700m3/h would be the minimum neccessary extraction.

It is important to remember that any restriction you place on the fan such as carbon filters, ducting runs and bends will cause a pressure build up in the ventilation system and will have the effect of reducing the amount of air the fan moves in and out of the room. So always go for more extraction to be safe. Buying carbon filters and fans designed to work together with ducting designed to work in a grow room environment makes a big difference.

When you add a filter you will reduce the capacity of your extractor fan. For example the RVK 150 L1 gives 720 m3/h so looks good but when you add a Carbo Air filter to this fan the capacity drops to 580 m3/h. So for our example the RVK 200 L1 moving 815m3/h with a filter would be a better option for our example grow room.

Ideally you will want to maintain a slight negative pressure within your grow room to prevent leaks and odours

We recommend up to a 25% reduction m3/h volume for the intake fan.

You can use a passive intake, where you don't have a fan and rely on the exhaust fan to pull air through but this really requires large enough vents in the room or tent to allow enough air flow.

Remember if you are drawing air from outside during the winter months this will be very cold and could damage your plants if directly exposed to an intake fan outlet - use a sheet of ply  to stop it blasting directly onto any plants and to help it mix with air in the grow room or better still take warmer air from inside the building.

TOP TIP: Always place your intake if not using a diffusing device at the bottom diagonally opposite corner from your exhaust fan. This helps ensure air moves across the whole grow area. Do NOT blow intake air directly onto your plants.

TOP TIP: Always invest in the best fans you can afford. They do wear out and you will be better served by a quality made fan.

TOP TIP: Always cover your intake vent ducting with a mesh or bug filter.

Circulation Fans and Air Diffusers

Circulating air is essential in any larger scale grow and is highly recommended for smaller grows too.

Circulating air prevents hot spots, micro climates, stale and hot air areas (especially around lighting).

Air will also form stratas, or layers, of hot and colder air within your growing environment as hot air weighs less than cold air. The colder air will drop to the floor areas and push the hotter air up around the lighting. This makes the canopy of the plants hotter and bottom colder and reduces the speed the plants grow.

You can use oscillating fans but make sure the model you choose is designed for grow rooms, as those not specially designed to operate in humid and very warm conditions often break down before a single grow cycle is completed.

You can also rig an inline fan to circulate the air by drawing cold air in from the bottom of the grow area and dumping it at the top above the light canopy and circulate the air this way. This is a better way than using oscillating fans.

The most advanced and recent methods involve new systems which have been specially developed to ensure freshly introduced intake air is fully mixed and agitated within the growing area. These 'Diffuse Air Systems' or air diffusers are capable of being attached directly to an RVK and an intake duct completely eliminates micro climates, pockets of heat and humidity high spots and helps ensure a stable and uniform environment throughout the grow room. An additional benefit is that as they are mounted at the top of a grow room there is more space on the ground level for plants to grow and thrive.

Fan Speed Controllers

Investing in a controller is essential to maintain the growing environment. A good controller will maintain temperature and humidity levels precisely.

Choose a controller designed for use on UK voltages as cheaper units from abroad can and do fail so we supply only devices that have been designed and tested by the industry.

By having a controller system in place at the earliest opportunity you will ensure you get the best results. You will see a better return on investment through healthier, more productive plants.

Extraction Fan Silencers

Reduce the noise in your duct work by adding a silencer. They absorb the noise created by fans and from the air hitting the sides of the duct work. Silencers remove a lot of unwanted noise; two can be used in series where unwanted noise is a particular problem. With the higher flow rates of our professional fans, air noise can become a problem. Air moving through ducts creates noise. The faster the air, the more noise is created. If noise is a problem connect a silencer to your system. They are most effective if positioned directly after a fan.

THERMOMETERS / HYGROMETERS / AIR SPEED METERS

Temperature

What is the perfect temperature for your grow room?

The answer of course is that it varies, depending on what you are growing and the amount of CO2 available. Ideally you should aim to be a couple of degrees either side of 24C when your lights are running. If you have higher CO2 concentrations in your room you can run a higher temperature. When the lights are off aka nightime you do NOT want the temperature to fall too much as this will affect your yields, so a heater unit linked to a thermostat to keep the nightime temperature to 2-3 degrees below your daytime temperature will be ideal.

Air Humidity

Maintaining a good humidity level will help maximise yields, with certain fruits demanding high humidity levels while flowering plants require less as their life cycles progress.

Understanding humidity levels is crucial to a good result. Changing the humidity levels through light cycles is also beneficial. Young plants can benefit from a higher humidity around 70% with the night cycle dropping to around 55%. As plants grow you can allow the level to drop to 65% - 60% as fruit / flower sets start to appear. As crops reach maturity you want a humidity level of around 55% to finish. You can take it down to 53% if the crop's flowering density is high.You should aim to have a night time humidity of around 50% towards the end of a crop's life cycle.

You can control humidity by having a humidifier and dehumidifier setup on a controller that monitors the levels and switches on each when needed. Automating this process will keep your growing environment stable without large deviations, causing less stress to your plants keeping them happy and healthy and allowing them to spend their energy on growing and yielding rather than coping with drastic climate changes.

DUCTING and FITTINGS for DUCTING

Always try and minimise the number of bends as they do cause back pressure and make your fans work harder. Keep ducting straight where possible and as short as you can.

CARBON FILTERS

We stock a range of carbon filters to eliminate odours emanating from a grow room. Carbo Air filters are specially designed to fit and work with RVK fans. We also stock premium filters from the Dutch Touch Pro range.

Setting up a carbon filter means you need to consider your intake airflow. You need to draw in clean, fresh CO2 rich air for your plants to grow. To do this you need a fan for intake and ideally this should run at LESS m3/h than your extraction. This will achieve a negative pressure within the grow room and protect it from leaks of unfiltered air and odours.

We recommend up to a 25% reduction m3/h volume for the intake fan.

You can use a passive intake, where you don't have a fan and rely on the exhaust fan to pull air through but this really requires large enough vents in the room or tent to allow enough air flow.

Remember if you are drawing air from outside during the winter months this will be very cold and could damage your plants if directly exposed to an intake fan outlet - use a sheet of ply to stop it blasting directly onto plants and to help it mix with air in the grow room, or better still take warmer air from inside the building.

When you add a filter you will reduce the capacity of your extractor fan. For example the RVK 150 L1 gives 720 m3/h so looks good but when you add a Carbo Air filter to this fan the capacity drops to 580 m3/h.

RVK and Carbo air filters provide graphs to show the effects on air flow to aid you making the right choice.

Grow Room Heaters

Run a cheap oil filled or tube heater in your grow room with a thermostat and timer for night (and colder days). Let your main controller and fan setup monitor and maintain the right temperature.