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[Lesson In Lamps] Running Lamps (Part 3 of 3)

[Lesson In Lamps] Running Lamps (Part 3 of 3)

So you've chosen a grow lamp - here's how to use it.

This is part 3 of a 3 part series.

Here's you'll learn how to run your grow lamps properly.

Running Lamps

To power your lamp, you need to run it as part of a lighting system, with a:

  • lamp
  • ballast
  • reflector

Your ballast powers your lamp.

Your reflector determines your light footprint.

Choosing A Lighting Cycle

During vegetative growth, you should run lights on an 18hr cycle (18hrs on / 6hrs off). Doing this mimics the longer days when plants normally grow. This keeps plants in a vegetative state

To trigger flowering, switch to an 12hrs on / 12hrs off. This recreate the shorter days when plants normally push out fruit and flowers.

Setting On / Off Times

To set on/off times, you need:

  • a timer
  • a contactor

It's your timer's job to turn lights on and off at chosen times.

It's your contactor's job to protect your timer from high inrushes. If you've got an HID light, you really do need one.


Without one, your timer may fail, and lights can be left permanently on. This'll disrupt your lighting cycle, at best.

Setting Up

1) Suspend the reflector in place

2) Firmly screw the lamp into the lampholder

3) Plug the lead coming from the reflector into the ballast

4) Connect the ballast power lead into the output socket of the contactor

5) Plug the contactor ‘input’ lead into the mains

6) Plug the contactlot ‘timer’ lead into the timer

7) Set your light on times, using the timer

8) Plug your timer into the mains

You are now in a position to safely switch on the mains.

Light systemLight system

Replacing Lamps

Like most things, lamps degrade over time.

The problem is, every 1% of light lost costs you roughly 1% of your yield. It's important that you replace lamps regularly to keep your yield consistent and high.

For most lamps, this is around 6 months. For higher end lamps (like Gavita!) you'll be good for 1 - 2 years.

Have a spare lamp handy, just in case. You never know when you'll need one quickly.
About the author

Ian's our Sheffield shop manager. He loves tinkering in the greenhouse. Drop by to see what he's growing.

GroWell Hydroponics Sheffield

Call GroWell Sheffield:
0114 243 9242

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