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How to Build a Grow Room on a Budget

How to Build a Grow Room on a Budget

18 Aug 2016

Ready to set up a grow room? It doesn’t have to cost the earth. Here’s how you do it on a budget.

Find a Kit

The easiest & cheapest thing to do is to get a grow tent kit

  • Easier - skip the sizing up (lights, tent & extraction are included)
  • Spend less- it's cheaper buying a kit than it would be to buy everything on its own
  • No mistakes - we've hand picked everything in these kits to give you great results

If a kit's not for you, you can do it yourself.

Do it Yourself

For most people, there are three main steps involved:

  • Choosing your lighting
  • Picking a tent
  • Controlling your climate

1. Choose your Grow Tent

The size of your tent needs to suit your grow lights. As a rule, here’s how much space you need for each grow light:

Light Coverage
  Footprint Height
250W light 0.75m x 0.75m 200cm
400W light 1m x 1m 200cm
600W light 1.2m x 1.2m 200cm
750W light 1.2m x 1.2m 200cm - 215cm
1000W light 1.5m x 1.5m 215cm - 240cm

If using fluorescent propagation lights, you only need a small propagation tent, because the light intensity is so low. 

Grow Tents Grow Tents

When sizing up your tent, make there’s enough space for ducting at the top and sides of your tent.

Money Saving Hint:

Pick a tent that’s going to last. It may be more to buy, but if it lasts longer, it costs less overall.

2. Choosing your Grow Lights

There are lots of lights to choose from. For their main grow, most people use an HID light, with or without supplemental lights. 

Most of the time you'll be using a CFL light for propagation, then switching to an HID lights for your main grow. 


CFL (compact fluorescent lamps)

These lights are very low power and the only ones suitable for use in propagators.

Most people only use them on cuttings, seeds and mother plants. 

Budget CFL: T5 Propagation Grow Lights

Best CFL: Bright-Wing Mother Clone Light

HID light HID light

HID (High Intensity Discharge) lights

Mostly emit wavelengths used for growth, from the ‘PAR range’ (400nm – 700nm). These lights are made up of a ballast, lamp and reflector.

  • HPS (High Pressure Sodium) - mostly red light for flowering
  • Metal Halide (Metal Halide) -  mostly blue light for veg
  • Dual spectrum - emit blue and red light, for veg & flowering

Budget HID: BAY6 Lighting System (choice of reflectors)

Best HID: Gavita 400V E-Series Lights  or DLI Joule-Series1000W Lights


Supplemental grow lights

These lights are used alongside your main HID lights to improve yield taste, aroma, appearance & quality.

  • 315W CDM (Ceramic Discharge Metal Halide)
  • 270W LEP (Light Emitting Plasma) 

With the right reflector, in the right area, you can use 315W CDM as a standalone light. 

Budget Supplemental: Maxibright CDM Lighting System

Best Supplemental: Gavita LEP Plasma Grow Light


LED grow lights

LED grow lights are are cool and cheap to run. Lots of growers switch to them in summer.

The thing is, they're hit and miss. Cheap ones don't emit a good enough spectrum or penetrate far enough into the canopy layer. But the good ones are very good.

The ones we sell (GN Telos) emit at least 2.1μmol per W - that'll give some of our best HPS lights a run for their money.

Best LED: Telos LED

BAY6 Ballast BAY6 Ballast

Ballast Types

Choosing a ballast (if running HID lights) is a lot easier. You've basically got two choices - magnetic or digital.

Magnetic ballasts: Are cheaper to buy and get the job done.

Digital ballasts: Cost less overall (cheaper to run, last longer, prolong lamp life) 

Lighting Layout Lighting Layout


Your light coverage is determined by your reflector (if using HID) lights. So the shape of your reflector needs to match the shape of the growing area.

The easiest way to get it right is to split your grow tent into sections, then position a reflector in the centre of each section.

Budget Reflector: BAY6 Euro

Best Reflectors:  Adjust-A-Wings

Money Saving Hint:

Consider running your grow lights at night . You'll spend less on electricity because night time tariffs are lower.

It’s also cooler at night, so fans or air con systems don’t have to work as hard during summer. 

3. Set Up your Climate Control System

There are two ways to do it. You can exchange air or create a closed loop room. 

Exchanging air

This is where you extract stale, hot, humid, CO2 depleted air and replace it with cooler, less humid, CO2 rich air. You also need to remove any odours before extracting air.

Silenced Revolution Silenced Revolution

You need:

  • Extractor fan
  • Intake fan / intake vents
  • Ducting
  • Carbon filter
  • Fixings
  • Fan speed controller (optional)

The easiest thing to do is buy an extraction kit and expand on it if you need to.

Budget Kit: Eco Extraction Kit

Best Kit: Silenced Revolution Vector Kit with an Enviro Controller

To work out how many cubic metres of air your fan needs to extract an hour:

Step 1

Multiply your tent's L x W x H.

The answer is how much space is covered by your grow lights.


In a XL BAY6 Tent:

1.2m x 1.2m x 2m = 2.88m3

Step 2

Multiply this by 60

That'll tell you how much air to extract every hour.


In a XL BAY6 Tent:

2.88m3 x 60 = 172.8m3

Step 3
  • Add 20% for a warm attic
  • Add 20% if using a carbon filter
  • Minus 15% in a cool basement
  • Add 20% for long ducting
  • Minus 25 - 30% for air cooled lighting

If you’re only extracting a small amount of air, you can get away with drawing air in through vents. Otherwise, pick an intake that draws in 20% less air.

Money Saving Hint:

To cut costs, swap your RVK fan for an EC fan To read more, hop over to EC vs. AC fans.

To Create a Closed Loop System:

For complete climate control, you’ll one a closed loop set up. Hardly any air enters, hardly any air leaves. Instead of exchanging air, you constantly treat the air with a climate control system.

Grow Room Grow Room

Hardly any air enters, hardly any air leaves. Instead of exchanging air, you constantly treat the air with a climate control system.

Best Option:

Don’t forget that you will need to add CO2 and dehumidify the air in a closed loop set up.

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