There are a lot of misconceptions and myths in the marijuana growing world, and the subject of lighting has no shortage of them. The exploding bulb is one of my favorites.
Before I proceed, let me state emphatically - I love my LED fixtures.But, I want to take this opportunity to dispel some things that pop up on this forum from time to time.
@Eagergrower I can assure you there is no danger of a bulb exploding or a fire happening when an air-cooled fixture is used. There may be a slim possibility of a bulb breaking if you had an open bat-wing fixture and you sprayed it with water, but you would never be in that situation anyway because you would never run an open fixture after reading this.
As far as energy cost savings go, like I said earlier - it really depends on where you live. I went ahead and did a quick comparison. Based on the U.S. national average of 12 cents/kilowatt-hour and the following for a typical 4x4 tent:
600 watt air-cooled HID fixture with digital dimmable ballast ($230 initial cost)
(2) HLG 260 XL fixtures ($660 initial cost)
At a $344/year operating cost (including a replacement bulb every 12 months) for the HID fixture, and a $264/year operating cost for the LED, the break-even mark is right about at 5 years ($1950 versus $1980). Changing the LED to a single HLG 550 economy model, the break-even is just under 5 years.
Regarding heat removal - there is no additional cost because you simply connect the fixture to your existing exhaust fan.
Vertical height: My big 1000 watt setup is a whole 10 inches tall, and an HLG 260 is 2.5 inches tall. Maybe it would make a difference if you were at the very top of your tent and couldn’t go any higher, but if your plant is that tall, you likely are going to run out of room regardless which fixture you have.
Now, on to heat. This is where the big misconception lies, undoubtedly because of the reputation of the old open bat-wing and parabolic HID fixtures. In actuality, an air-cooled fixture can be cooler than an LED fixture. Here is a comparison of 3 different lights. Note this is with a 1000 watt fixture, which is actually much more than needed for a 4x4 tent.
Canopy distance - I guarantee you I could not do this with my LED lights. They are right up against the glass. My flowers would be burnt to a crisp with my LEDs.
As far as what is now/future… many growers prefer CMH over LED. There may also be a future for plasma lights if they can bring down the cost and increase the bulb longevity. The plasma light spectrum has potential.
So, after this long diatribe, the main thing I want to leave you with is:
Given the choice and if you can afford it, I would absolutely recommend purchasing an LED fixture. But only a good one. LED lighting is fantastic. Cheap LED lighting will only disappoint you. If you can’t afford a good LED, I would much rather see a person purchase an air-cooled HID light than a blurple LED on Amazon, which sadly happens far too often.