Advice on LED

[ConstantGreen]

Because so many LED's in such a compact area is so intense, you can't use most LED panels closer than 18" or you'll burn plants. 18" high for the reflector192 gives ~150 PPFD in the 4x4 ring. This is barely adequate to root a clone in.

Yes, spreading out the LED's, you get the same energy going to your plants but the light doesn't have to travel so far so you're getting the best intensity of it as you can hang your LED closer to the canopy. Spreading the LED's apart also gives better intra-canopy penetration. The amount of PPFD reaching your plants when 600w is spread out vs 600w centered is a huge difference of efficiency for your electrical cost.

Not sure if parts of plants share PPFD but that's something I've wondered about too. But considering the lower nugs on a plant are so often larfy and undeveloped, I think each flower site kind of depends on its own PPFD. Better coverage and penetration will lead to better flowers in the entire 4x4 footprint. You could wait longer, but I don't think it works that way. If a nug is developing at 50% for 8 weeks, it's not going to be a top-quality nug at the end of 16 weeks. The plants have a genetic timer and your end result depends on how well you energize her during each day of that ~8 week timer.

 

[Ripe1]

Not sure if I believe it either. I would assume that LED's being more efficient would put off less heat. But from what I've read it's negligible. My 660w Spydrx Plus still puts out a lot of heat. Only difference is HPS puts out radiant heat that warms the plants and everywhere the light shines. LED's don't give off much radiant heat, it mostly rises from the unit to the ceiling.

In my experience, leds produce almost no heat, at least mine doesn't. On cold days I need to add heat. Even with a small t5, I'm still staying at 78 to 85 degrees. Light burn is more of a concern with the extra focused lenses on LEDs.

 

[Merkle420]

Because so many LED's in such a compact area is so intense, you can't use most LED panels closer than 18" or you'll burn plants. 18" high for the reflector192 gives ~150 PPFD in the 4x4 ring. This is barely adequate to root a clone in.

Yes, spreading out the LED's, you get the same energy going to your plants but the light doesn't have to travel so far so you're getting the best intensity of it as you can hang your LED closer to the canopy. Spreading the LED's apart also gives better intra-canopy penetration. The amount of PPFD reaching your plants when 600w is spread out vs 600w centered is a huge difference of efficiency for your electrical cost.

Not sure if parts of plants share PPFD but that's something I've wondered about too. But considering the lower nugs on a plant are so often larfy and undeveloped, I think each flower site kind of depends on its own PPFD. Better coverage and penetration will lead to better flowers in the entire 4x4 footprint. You could wait longer, but I don't think it works that way. If a nug is developing at 50% for 8 weeks, it's not going to be a top-quality nug at the end of 16 weeks. The plants have a genetic timer and your end result depends on how well you energize her during each day of that ~8 week timer.

Wrong, I've got 5 led's although not too range still powerful, they hang 8-13 inch's In flower depending on the strain.

 

[ConstantGreen]

In my experience, leds produce almost no heat, at least mine doesn't. On cold days I need to add heat. Even with a small t5, I'm still staying at 78 to 85 degrees. Light burn is more of a concern with the extra focused lenses on LEDs.

LED's still produce heat, it's just radiated differently:

You can't say LED's produce less heat unless you know the umol/J of the lamp. The latest HID tech is just as efficient as LED in terms of PAR produced per joule of energy, so the amount of heat waste is similar.

"The two most efficient LED and the two most efficient double-ended HPS fixtures had nearly identical efficiencies at 1.66 to 1.70 micromoles per joule. This is a dramatic improvement over the 1.02 micromoles per joule efficiency of the mogul-base HPS fixtures that were in common use 10 years ago."
https://www.google.com/url?sa=t&rct...iversity.pdf&usg=AOvVaw2lGHUnJgFiP6iPW_Bqznzc

Wrong, I've got 5 led's although not too range still powerful, they hang 8-13 inch's In flower depending on the strain.

That's why I said "most LED panels", specifically the ones I've done extensive testing with, like the Reflector 192. No statement will account for every variety of LED light out there. The closer you can hang your LED, the better.

 

[Grassmaster]

4 (107 watt) COB's placed in the corners of your tent is a direct replacement for a 600 watt HPS. Like a MIGRO 400. Similar results to a 600 HPS, with almost no heat directed at the plants.

[video=youtube;f3JQgMfZgHs]

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[The rooster]

A 600w LED still puts out similar heat to a 600w HPS. Among LED's, some will have higher efficiency, turning more electricity into light instead of heat. Some of the most efficient LED lights on the market are built by Fluence Bioengineering, with over 2.1 µmol / watt. Most manufacturers won't list that statistic though. A good 600w HPS light is about 1.8 µmol / watt. A cheap LED light could actually be less efficient than what you use now.

If heat is your main concern you'd be better off adding a closed reflector with air ducting to your HPS.

I want to hear your take on spectrum king because your always spot on

 

[Stltoed]

Spectrum King Closet Case

It's nowhere near strong enough

 

[Stltoed]

Probably a Spectrum King 400 or 600 with a dimmer and 120 degree reflector would duplicate what he's doing. A closet case is only for a small area.

SK sucks. It's bright, but beamy. It's not a cool running lamp. But, I have used a duct attached to the heatsink to pull air through with great success.

I am presently using a 400+ in a tent. I only have it because I couldn't sell it and selling my old lights wasn't about money I simply needed room. I have had it for a while. The design is really cool. The dimmer is a must. The white light makes pictures easy, but I really don't like their product.

I replaced my SK with two from a competitor. The day after my plants were visibly happier. Leaves up and ready to go. The SK lamp just doesn't inspire growth... I understand this is kind of wierd. You can see a diagram of their spectrum... looks cool, but for whatever reason it doesn't transfer to strong plants. I don't know.

There are plenty reviews of their lights. Some seem to do very well. Remo himself was just in a review of theres. I just haven't seen it.

 

[Ripe1]

I have vipar spectra's now. They are decent but if you really want something to replace that hps I would suggest Black Diamond Perfect Sun. They are a site sponsor, the owner is an active member here and offers discounts on some of his products to site members. I will be upgrading from the vipar spectras soon. I honestly think the perfect sun led's are the very best on the market, from what I can tell.

Mars Hydro is another site sponsor you may want to look into. They also have active members on this site and lots of people here grow with their leds.

Check out the site sponsors

I have to agree with Merkle and LALG. I have the VS PAR700, it was rough on my auto seedlings, (I think they were all just bad seeds) but my new Photos and the 1 auto cheese that survived are killing it in my tent. I now use a $60 T5 for seedlings. Let me stress the point that I am 99% sure it was the seeds and not the light. My temps are in the high 70's 95% of the time & with a Vicks vaporizer NOT pointed at your girls but pointed at a fan that is in turn pointed at the girls, you can enjoy 50-60% humidity. I also add a regular humidifier to help bring the temps down if they start getting in the low 80's on warm days. Sit back and watch. Good luck Stupot!