Build Your Own Air-Cooled HID Grow Lamp

Author: Katherine Keleher

Article: Hydroponic growing gives home hobbyists great flexibility in designing their indoor gardens. Through clever design, a gardener can convert everyday household items into useful hydroponic equipment, at a fraction of the cost of commercially pre-fabricated products. This example uses a couple of 70w parking lot security lights from the local Home Depot/Lowe's/Wal-Mart-type store to build an inexpensive air-cooled grow light.

First, you need to decide what lights you are going to convert. These can be HPS or MH, both types of bulbs are very similar for hydroponic growing applications. (More information on the different types of grow lights can be found at http://www.indoor-gardening-guide.com.) Any size between 40 and 150 watt will work fine in this setup. Used lights will work just as well as new or you could check the prices at one of the many online light distributors. New or used, the total cost for this air-cooled grow light project shouldn't be any more than a hundred dollars.

Larger light bulbs will require more ventilation and a bigger cabinet than the one used here. This project can be scaled up to accomodate bulbs of any size just by following the same steps with a larger cabinet and glass piece for the heat shield. Because most of the parts used for this conversion are common household items, the additional cost for a larger box is minimal. If you can afford a larger HPS or MH light bulb, you can easily build an air-cooled cabinet for it.

Disassemble the old lights, setting the sockets and ballasts aside for later. Make sure you keep any brackets, screws, washers, etc., as you may need them later. You can discard the motion-sensor, if it has one, or keep it for another project, but you won't need it now.

Set aside the grow lamps and parts you've decided to keep. For the box, I used an old dresser drawer, but any solid, heat-resistant box will do (not plastic or Rubbermaid, it will melt from the light's heat). You'll need a piece of glass for the heat shield. It can be as small as a square foot, just so long as it covers the area where you will mount your bulbs. Most new security lights come with some type of heat shield, so you can use that if you purchased new or can find usable salvage parts.

If you also chose to use a dresser drawer, you'll find that your box is far too large for the size of your grow lamps. Mark the area needed to hold the glass heat shield in place and cut the drawer down until it fits. Use the wood from the unneeded drawer length to make up the sides of your box, or use other scrap wood until you have a nice tight fit. Most dresser drawers have a groove where they fit into the dresser's frame. You may be able to use that to hold your glass shield, depending on the size.

Look through all the screws and brackets we set aside after tearing apart the old lights. Hopefully, you will be able to find something that will fit where you want to mount your new garden grow lights. If there are no suitable brackets or mount pieces, you should be able to find something usable at the local hardware store. It doesn't have to be fancy, just some way to secure your bulbs so they won't move around inside the air-cooled box we're building.

Now you need to add ventilation to your box to prevent overheating. Plasting ducting works very well for this purpose because it is flexible and can be stuffed through oval holes when desired. This allows you to cut a smaller hole in the sides of your light box while getting better airflow over your bulbs by using a wide, flat oval hole for ventilation. This box uses a 4"" hose, with an oval hole about 5 inches wide and only a little over 2 inches high. Try to position the holes so the airflow will go directly over your bulbs, not in the center of the bulb where the air will just get stuck in the socket assemblies.

Line the inside of the box with foil to increase the light reflection. Even better would be to include a cheap metal reflector, bent around the inside of your box so it creates a nice tight fit. Now it's finally time to mount the grow bulbs inside the box. Make sure you mount them where the hot bulbs will not be touching the sides or any brackets, screws, etc.

You can use almost any type of fan for ventilation. Old fan-type heaters, blowers, and computer fans are common household items that usually work well in hydroponic gardens. If you don't have any of these laying around, computer fans are usually the cheapest option. Check out the local Fry's/CompUSA/Circuit City-type store or (even better) shop around online for super-cheap computer parts.

Squeeze the ventilation duct through the oval holes you cut in the sides of the box. You may have to snip wires or extend them in order to make everything fit, depending on your design. Whatever you do, be sure to use the right kind of wire and splice ends properly. Wire is cheap, don't be tempted to skimp on this part and create an electrical hazard in your house. Drill a hole to pull the wires through, nail or screw the back on, and your box is complete. Connect the wires to your (recently-converted) remote ballasts and your air-cooled grow light is all ready to go.

The box at the end of this particular project ended up being about 11 inches square, with a nice air-cooled hood and two 75w HPS bulbs. It is expected to give off between 4,500 and 5,000 lumens, with almost no heat buildup. Not too bad for under a hundred bucks.

About the author: For additional <a href=""http://www.indoor-gardening-guide.com/garden-grow-lights.ht ml"">garden grow light</a> information, indoor gardening articles, hydroponic system comparisons, and more on hydroponics, visit http://www.indoor-gardening.guide.com.