Regardless of the name, LEC grow lights are basically a hybrid between Metal Halide and HPS grow lights. It is a type of Metal Halide bulb that is constructed with ceramic like an HPS. As a result, LEC grow lights last longer and are 10-20% more electrically efficient than MH lights. They also produce relatively high levels of UV rays, which may contribute to increased trichome development on cannabis buds, and can potentially make buds more potent.
The reason this can be such a problem with LEDs is it can take a few weeks before your plant really starts to show symptoms. Usually the upper leaves are affected first (yellowing or turning brown or spots) by too-close LEDs, but symptoms can also affect other parts of the plant.
For the best results with T5s and CFLs, try to keep the lights as close as possible and adjust them every day to prevent the plants from growing into the light.
If the leaves start pointing up like this, it’s a sign the plant is getting a LOT of light. Some growers like to see their leaves “pray” but if you see this keep a close eye to make sure leaves don’t start turning yellow early.
Sun System LEC Grow Lights
Same as with MH/HPS grow lights, always conduct the 30-second “hand test” after you’ve positioned your light. If the light bothers your hand after 30 seconds, it may bother your plants!
400W – covers 3′ x 3′ (0.9m x 0.9m) area up to 3.5′ x 3.5′ (1m x 1m)
Sunlight” distance on the chart and only move lights closer if your plants are stretching towards the light (getting tall and lanky).
LEC grow lights are surprisingly powerful and must be used with caution to prevent light burn, especially with seedlings and strains that tend to be more sensitive to light. This 315 LEC is being kept 2.5 feet (75 cm) away from the tops of these young plants until they get bigger. Some CMH models need to be kept 3 feet away from the tops of plants!
Each type of grow light (CFLs, LEDs, HPS, etc) has a "sweet spot" as far as how far to keep from your plants. Learn what the sweet spot is for your light!