LED systems run cooler per watt and need less ventilation to stay cool.
Interesting because the initial cost of LED's is so much higher to start, but with lower power bills for cooling and operation - they could be worth their while overall.
As an amateur, I started with a very small 150watt HPS light with ballast built in the fixture. Incrementally moved up to 250watt, 600 watt and so forth. Once 600 watt - the digital ballasts were out which would allow me to switch from MH to HPS as the ballast would run either bulb instead of one specific bulb.
What they're trying to do with LED's however, will prove awesome results once perfected. Here is a good video explaining it.
Cliffnotes - LED's are designed to cater to the usable spectrum the plant responds to. MH and HPS lights carry broad spectrums, but not all of it is used by the plants. People used to run combo HPS and MH lights to get a 'larger spectrum' - and many are now adding LED's to their HID gardens to accent with a COMPLETE spectrum. Some are using LED only.
Amazing how this industry is evolving with technology.
Once cost goes down and technology is improved, LED's are likely to be the #1 choice for small and large growers.
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