The Professional Grow Room

Grow Rooms allow a diverse range of plants to be cultivated in a completely controlled environment.

The ability to have complete control over climatic variables such as temperature, humidity, light, CO2, nutrition and the ability to shield out insect pests provides enormous benefits:

  • Crop yields are able to be dramatically increased.
  • Harvest times can be accurately scheduled with minimal losses.
  • Exotic plants (e.g tropical plants or alpine plants), which are not normally able to be grown in a particular part of the world, can be successfully cultivated in a grow room.
  • Agrichemical usage can be avoided completely.
  • The sterility of the crop and grow room equipment can be assured.
  • Airflow into and out of a grow room can be filtered and sterilised making them ideal for use as plant quarantine facilities.

A Professional Grow Room is one that is designed properly and has all the correct equipment being used at all the right times.

Intelligent control and careful design is therefore of utmost importance.

Pure Hydroponics is able to provide grow room controllers that are designed to precisely control every climatic or nutritional variable in the grow room and intelligently activate and deactivate grow room equipment to counter any eventuality.

All items listed in Blue lettering can be found on this website. For other items not listed in Blue lettering please contact Pure Hydroponics for information & pricing.

Control Equipment

For the intelligent & automated control of every aspect of a grow room environment we recommend the Intelli-Climate controller manufactured by Autogrow Systems in New Zealand.

The Intelli-Climate controller will take charge of:

  • Lighting
  • Air conditioning
  • Humidification
  • Dehumidification
  • Fans
  • CO2 injection equipment
  • Alarms

For growers that only require CO2 injection control we recommend the CO2 Easi controller manufactured by Harvest Master in New Zealand.

For the automated dosing of Nutrient and pH stock solutions in grow room hydroponic systems we recommend the Bluelab Dosetronic controller manufactured by Bluelab Corporation in New Zealand.

All control systems and growroom equipment is available from Pure Hydroponics at competitive Wholesale or Commercial Grower prices.

The following variables need to be  carefully considered and planned for when designing a grow room:


The grow room should have different daytime and night time temperature settings and a gradual blending of the two to simulate the natural outside environment.

Night time temperatures (dark phase) should ideally be around 5 degrees Celsius below the daytime temperatures.

The use of High Intensity Discharge Lighting will heat the air inside the grow room. To reduce grow room temperatures air conditioning units can be used or an air cooled lighting system (e.g Cool Tubes) can be used to strip any heat off the lighting bulbs and extract the heat outside the grow room before it can influence the air temperature inside.

Inlet fans should be used to provide fresh, cool air into the grow room and extraction fans should be used remove any warm, stale air.

The balance of these fans is important. The extraction fan should always be removing more air than what is coming into the grow room through the inlet fan so as to create a negative pressure.

This is important in quarantine situations as a grow room with negative pressure will suck air into it when any doors or windows are opened. This prevents contagions or odours from escaping through opened doors and windows.

Fan Speed Controller can be used to balance inlet and extraction fan speeds in order to create a negative pressure. It also provides the security of an extra level of temperature control by turning all fans to maximum speed if the grow room temperature climbs beyond a pre-programmed set point.

Carbon filters can be attached to extraction fans to remove any odours, spores and pollen from the extracted air.  Ozone Generators can inject Ozone gas into the extracted air to sanitise the air of any harmful organisms and remove odours.

In grow rooms where CO2 injection is available, it is not beneficial to use extraction fans when the CO2 is being injected as the fans will immediately remove the valuable CO2 from the grow room.  The use of air cooled lighting or an air conditioner will help to keep the grow room cool until sufficient time for CO2 absorption has occurred.

An Intelligent grow room controller such as the Intelli-Climate will maintain a steady air temperature in the grow room by manipulating  inlet and outlet fans and activating air conditioning units.

The grow room must be well insulated to limit any heating or cooling effects from the environment outside the grow room.

Modified chiller rooms or refrigerated reefer shipping containers are often popular to use as grow rooms as they already have an insulated lining.

Lining the grow room walls, roof and floor with white reflective Panda Film will promote a cooling effect and improve light availability to the crop.  The Panda Film will also provide a water proof barrier should there be any leaks in the growing system or moisture build up.


The level of air Humidity in a grow room affects the rate of plant transpiration, water uptake, transportation of nutrient, cell turgor (pressure & firmness) and overall growth of a crop.

Growers should aim to maintain humidity between 55 – 75% depending on crop type and age of the plants. If Carbon Filters are used to filter outgoing air, then humidity should be kept under 70% to enhance their performance.

Night time (dark phase) humidity levels should be lower than that of day time levels.

Inlet fans help to introduce less humid air into the grow room and the outlet fans remove the stale, humid air.

Oscillating fans help to keep the air circulating. This is particularly important for moving pockets of stagnant, humid air that can reduce rates of plant transpiration and contribute to fungal problems.

In a grow room with good air circulation all the leaves on the crop should be slightly moving.

A growroom which uses lights and CO2 injection will make the crop grow vigorously with a high rate of transpiration.  This will have the effect of raising the humidity.

In these situations a dehumidifier should be used to lower the humidity level. Air conditioning units also have a dehumidifying effect. The use of this equipment will save having to use the extraction fans during periods of CO2 injection and it prevents valuable CO2 from leaving the room.

During periods of low humidity the most effective way to raise the humidity in a grow room is to use low pressure fogging nozzles which can operate off mains pressure. These fogging nozzles should be able to produce fine droplets under 80 micron in size. The nozzles a can be pulsed automatically by a climate controller via an electric solenoid valve installed on the water pipe leading to the nozzles.

An Intelligent growroom controller such as the Intelli-Climate will maintain a steady humidity range in the grow room by manipulating  inlet and outlet fans, oscillating fans, air conditioning units, dehumidifiers and humidifiers/fogging nozzles.  The Intelli-Climate also provides for the automatic scheduling of humidity levels to accommodate the varying requirements of seedlings & cuttings right through to flowering stage.

CO2 Enrichment

All professional grow rooms should have CO2 enrichment.

When CO2 is maintained at between 1100 – 1500 ppm during the light phase, the increase in yields is incredible.

In many cases crop yields can be increased by at least 40% (depending on crop type) with a marked reduction in growth time.

CO2 is only injected during daylight (light phase) where it is used by plants for photosynthesis. During periods of CO2 injection the grow room should remain sealed with the inlet and outlet fans turned off and the lights on. Ordinary lights will emit heat and the temperature in the grow room can build up quite quickly forcing the controller or grower to turn the fans back on again to remove the heat and introduce cooler air to the room. This is wasteful as it will remove the valuable CO2 from the room and reduce the amount of time the plants have to absorb it. To overcome this problem air cooled lights should be used as well as airconditioning units. This will keep the room cool and allow plenty of time for the plants to absorb the CO2.

Bottled CO2 with a regulator and solenoid valve is the best way to inject CO2 into a growroom.  An Intelligent Growroom controller  such as the Intelli-Climate or a specialised CO2 controller such as the CO2 Easi can monitor the CO2 levels in the grow room and open and close the solenoid valve on the regulator to release more CO2 gas into the grow room until a predetermined setpoint is reached. The unit then goes on standby until the plants absorb some of the CO2 before more is released. After a set time period to allow for absorption of the CO2 the fans in the room are reactivated and all equipment and functions in the grow room return to normal.

Crop Nutrition

The supply of nutrients to the crop should be automatically controlled to ensure the correct amount of nutrients are supplied at all times and adjusted as the crop matures.

Most grow rooms utilise either a recirculating NFT Hydroponic System, Batched Dosing Drip Fertigation System or a Flood and Drain System. All three systems feed from a main tank containing a nutrient solution. Pure Hydroponics recommends a Bluelab Dosetronic control system to automatically dose nutrient and pH corrector stock solutions to the main tank.

For growers who prefer a step down in technology, the tanks can be manually dosed and tested with a Bluelab Combo Meter or Bluelab Guardian Monitor.

For the best quality nutrient in an economical powdered form talk to Pure Hydroponics for their Custom Batched Nutrient.


Most grow rooms rely 100% on artificial lighting.

Fluorescent tubing or Metal Halide lights (or HPS – MH converter bulbs) are mainly used for vegetative crops or the vegetative stage of a flowering crop.

High Pressure Sodium (HPS) or LED lights are used for the flowering stage of flowering crops.

Please see the section on Hydroponic Lighting on this website for more information.

During the Vegetative Stage of a crop a lower level of light is required by the crop for longer time periods – usually 18 hours of light, followed by 6 hours of darkness.

During the Flowering Stage of a crop a higher level of light is required for shorter time periods – usually 12 hours of light, followed by 12 hours of darkness.

The lighting system in a grow room is often divided into 2 banks of lights which can be alternated. Only 1 bank of lights is used during the vegetative stage and both banks are used during the flowering stage to give more intensity. The adjustment of the height of the lights and the angles of reflector hoods can also increase or decrease light intensity.

Light Rail Movers are also an excellent way to simulate the natural movement of the sun and they provide light at a range of angles to the crop.

A rail which is long enough to fully cover the growing area of the crop is installed above the crop and lights are suspended from a silent moving motor which rides on the rail.

The motor moves along the length of the rail, pauses at the end and then slowly travels back in the other direction. This allows for more uniform growth of all the plants from top to bottom as they all receive the same amount of light with less shading of one plant over another. The use of a Light Rail Mover also allows a single bank of lights to cover a larger area meaning that you can get the same yield from using fewer lamps at only half the power cost.

An Intelligent grow room controller such as the Intelli-Climate will automatically switch lights on and off and active banks of lights in sequence so that all the lights do not come on at once and cause a power surge. The Intelli-Climate also has a light sensor which gives it the capability to detect a bulb failure and switch over to another bank of lights to improve intensity.

Alarm Functions

Grow rooms are heavily dependent on technology to produce a successful crop and not all growers can be on site at all times. An integrated detection and alarm system is therefore essential. The climate control system should have the capability to detect and alert growers of any equipment failures or any climatic variables which have exceeded the grower’s pre-programmed set points (e.g temperature or humidity too high, lighting intensity reduced etc).

Alarms can be in the form of an audible alarm sounding on a PC connected to the controller, an LED warning light system installed outside the grow room, or the ability to send an alert message to a mobile phone via a modem.

An intruder alarm triggered by a magnetic door switch is available to alert growers that the security and sterility of the grow room has been breached. This is particularly useful for quarantine facilities where security is of utmost importance.

All the above-mentioned features come as standard on the Intelli-Climate controller.

Remote Operation

The latest technology allows growers to access their grow room controllers from anywhere in the world to check on their grow room and adjust any settings via an internet connection, all with password protection.  The use of camera systems connected to the internet also allows growers to keep a constant eye on their crop. This frees up valuable time for the grower so they do not have to visit the site to continually check on their crop.

We trust that this page provides growers with some good advice on establishing a professional grow room and how to produce the perfect crop.

All the required equipment is available from Pure Hydroponics along with friendly and experienced advice.