THE GROW SHOW - CHOOSING THE RIGHT LIGHT

story & photos by Kyle Kushman
It's obvious that high-intensity discharge lamps (HIDs) are the choice for anyone serious about indoor horticulture. It's also unanimously believed that high-pressure sodium (HPS) is the best overall light when deciding between HPS and metal halide (MH). Lately, I've found myself defending my choice of 600-watt lights over thousands of watts. I'm convinced that 600s are the best option for indoor gardeners.
That more watts or lumens equals higher yields is absolutely true. But bigger isn't always better. Thousand-watt lights are not for amateurs. If your grow space is 150 square feet or more, you'll probably want to utilize 1,000s. But if you're growing primarily for yourself and would like to save electricity, then consider what 600s can do. (Four-hundred-watt lamps are out of the question for any serious bud production.)

Forty percent less heat means that the lights can be 40 percent closer to your plants without burning them. This alone cuts the difference in efficiency between the 1,000-watt and 600-watt lamps nearly in half. The placement of lights—especially always maintaining the perfect height in relation to your plants—is essential to extracting maximum yield. The highest yields and densest buds come when lights are kept close as possible. During times of peak growth, you should adjust the lamp height every day. Set-it-and-forget-it growers should stick with 1,000-watters.

Twelve inches or closer to the plant tops is recommended with 600-watt bulbs, though the distance will vary somewhat depending on your ability to cool the lamps and the surrounding area. After colas form, back off an additional 4 to 6 inches to prevent scorching. Once plants and root systems are established, blast the plants with light. Intense light is the key to developing close internodal spacing during vegging and early flowering.

Multiple points of light ("inversion lighting") will encourage the entire plant into rapid photosynthesis more efficiently. More direct light comes into contact with all parts of the plant, resulting in faster growth rates and more developed buds. Believe it or not, more lights with lower wattage actually produce higher yields.

Initially, it costs more to purchase five 600-watt ballasts than three 1,000s. Using less wattage is obviously cheaper, but the reduction in the heat produced adds to the electrical savings by reducing cooling requirements. In case of a blistering heat wave, you'll have the flexibility to cycle some lights off without leaving large portions of the growroom in the dark.

Amazing as it sounds, with 600 watts it's possible to reap 80% or more of the yield you can get with a 1,000-watter. The only drawback is that nobody makes switchables or metal halides in 600 watts. A good conversion bulb by either Sunmaster or Solar Max will fix that. Check out the Gavita 600-watt HPS lamp with built-in reflector. I rated it the Best HID Lamp in the 2002 STASH Awards.

The inversion-lighting method depends heavily on the proper positioning of the lights. A good reflector is also essential to extracting efficiency from any lamp. Air-cooling your lights can help you to gain tangible control over environmental conditions, which is essential to maximizing any grow.

So you still think you need a little more juice than a 600-watter can provide? Hybridize your lighting by hanging a 1,000-watt MH among three or four 600-watt HPS lamps. Trust me when I say that blending HPS and MH at a ratio of 3 to 1 is the ultimate equation. Combining the two lamps yields higher-density buds than HPS alone.

Overkill is okay with fans, filters and general safety precautions, but not when it comes to wasting electricity and dealing with added heat buildup. Six hundreds are excellent, efficient lamps; so are 1,000s. But the truth is, with a little extra attention, three 600s will yield as much and possibly more than two 1,000s. As will six to four—same yield, less power.


READ THE FULL ARTICLE IN THE JUNE 2005 ISSUE OF HIGH TIMES