Indoor Grow Light
Selector Tool
What Type of Light?
Welcome to the grow light selector tool. Let's get started.
If you are using this area to grow clones or seedlings, than use a fluorescent light.
If you are using this area to grow vegetative stage plants to 18 inches tall or less, than use 3 to 5 fluorescent lights or a metal halide light.
If you are using this area to grow vegetative stage plants larger than 18 inches tall, than use a metal halide light.
If you are using this area to flower plants, than use a high
pressure sodium light.
What Size Light?
If you have choosen to use a metal halide light, your goal is to light your garden area with 40 to 50 watts/sq foot.
If you have choosen to use a high pressure sodium light, your goal is to light your garden area with 50 to 80 watts/sq foot.
Measure the floor space of your garden area (example: 2 feet by 4 feet= 8 sq feet). Next, multiply this by the watts per square foot you would like (example: 8 sq feet times 50 watts/sq foot= 450 watts).
CALCULATOR COMING SOON
In the above example, I would need 450 watts of light to put my 2 foot by 4 foot garden at 50 watts/sq foot.
They do not make a 450 watt light, and so I would go with a 400 watt light in this example. I am confident I will still be close to the 40-50 watts/sq foot range.
Your possible light sizes are...
- 250 watts
- 400 watts
- 600 watts
- 1000 watts
You must choose the light that most closely fits your gardens needs. Keep in mind, a 250 watt garden will have a smaller yield. Also, I do not personally recommed 1000 watt lights. Check out this hot tip for the whole story.
If the light selector tool has led you to a metal halide or high pressure sodium light, there are a few system options to consider. Lets look at a few of them...
The light selector tool really comes in handy for this part. A light reflector like this, that is not enclosed and not air-cooled by an exhaust fan, sends all of its heat out into the room, (where you must use a good exhaust fan to deal with it).
If your garden area is open to freely exchange air with a larger room, this is the only time I would consider using this type of light.
Most of the time, however, your garden area will be fully boxed in, in order to be able to provide a dark period to force flowering. That is why I do not recommend these reflectors.
With the light fully enclosed and glass in the bottom, you can attach the light to an exhaust fan and control most of the heat at its source. Most of the heat will never enter your growing area.
The less your airflow is obstructed, the better the cooling effect will be. Lets take a look at a few more things to consider.
A reflector with exhaust vents like this is better than a reflector with no exhaust vents. However...
when you turn the reflector over, you can see how the airflow will be slowed down by the tiny vents inside.
Even if this reflector had good, 4 inch vent holes all the way through, the airflow would still run into the bulb and be forced to flow around it (slowing the airflow).
This reflector, vented corner to corner, has the same problems.
In this two bulb system, you can see how the airflow would pass through the reflector in between the two bulbs (not blocking the airflow at all). This design is better, but there is still room for improvement.
The 6 inch vent holes in this reflector go all the way through, allowing a maximum airflow through the reflector.
Looking underneath, you can see how the air moves unblocked through the reflector, past both sides of the bulb (and not right into the bulb). This design provides the maximum, unobstructed airflow (therefore the maximum cooling benefit). This is the design that I use myself.
To check out all the other stuff that I use myself, check out Jason's setup.
The light selector tool would not be complete without a section on your ballast. A ballast is a heavy electrical part that comes with every grow light. The ballast uses your home electric and "bumps up" the current to run high intensity discharge lights properly.
The biggest consideration with your ballast is the extra heat it generates.
Most light systems, like example above, attach the ballast to a long cord. This allows you to place the ballast in another area outside the garden area. This is called a remote ballast.
Compared to having the ballast IN the garden area, the difference can be as much as 10 degrees.
This is exactly the type of light you do NOT want to get. This light reflector is wide right here because it has a built in ballast, forcing you to deal with the extra heat inside your garden. I do not recommend using this type.
More recently, another option has become available. This is the digital ballast. A digital ballast uses computer chips to draw and produce exactly the electricity needed to run your light in a way that maximizes its light output.
A standard ballast uses a coil to do this. The coil has a cycle to control electric output. At the top of each cycle, there is a little extra energy than is needed to run the light. This extra energy is wasted each time as the cycle starts over (which is constantly).
The end result is that a light run by a digital ballast will constantly put out slightly more light, and will do it using about 1/3 less electric.
For my next system, I will have a 600 watt light with a well vented reflector and a remote digital ballast.
Getting the Best Lighting
From Your New Light
By now you have choosen a light with the grow light selector tool. The best lighting tips for your newly selected grow light can be found in one of the following areas...
Thank You for Using the
Grow Light Selector Tool
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