Need help with understanding LED lighting

I am not new to the growing game but i am new to the cannabis grow. I have never used LED lights before and really need some help laying things out for me. I know its all based on the spectrum of light compared to how many kelvins. But other than that I am at a lost.

This might help you a little, not what you were asking exactly but might be useful.

http://ledbuilder.org/index.php?threads/demystifying-led-grow-lights-led-grow-light-buyers-guide.34/

FYI: Duplicate thread: https://www.rollitup.org/t/need-help-with-understanding-led-lighting.894785/

From the other thread:

Tyrone Smith said:

az2000 i have a small grow space that is 18"x36".... is there any LED setup that is worth my time?

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Are you saying 18" square, and 36" tall? (If not, how tall?). LED lightbulbs would work well at around 20-30w/sq ft. Some people have used SMD5630 strip. I want to play with it but haven't yet.

Threads about strips:

Rigid, high-output strips

Redbird LED strip-kit (4' x 44w)
Some people may walk you through making your own DIY COBs run at low wattage (for smaller space). That would be more initial cost, but more, longer-term efficiency.

Other than that, I think T5HO is your best choice (if you have 36" width). The inexpensive LED UFOs would work if you found one with 3w diodes mounted on white backboard. It's the reflectors, secondary lenses, and/or 5w chips which make many of those fixtures unsuitable for your space (assuming it's short). But, those inexpensive LEDs aren't a good investment. I think you'd be better off with more efficient lightbulbs. But, a UFO is certainly easier to setup.

I haven't grown with it yet, but I'm really hopeful about the 10w GE BrightStik. The way the diodes face forward (instead of omnidirectional like the Cree lightbulb), it produces 22-25% more light mounted in a clamp-on reflector. That's alot of light for $3.50. (I tested it with the plastic diffusor removed. There is a shock hazard. Because the diodes are flush mounted, there's not a lot of surface begging to be touched. But, still, if you required absolute safety you'd want to power them through a GFI outlet.).

Sorry I wasn't clear it is 36" long 18" wide and 50" tall

Tyrone Smith said:

Sorry I wasn't clear it is 36" long 18" wide and 50" tall

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I have a 48" tall tent and the most intense LED fixture I can use is a 3w mounted on white backboard (no secondary lenses; no reflectors). The leaves can get to 2" from the glass. It's a Blackstar 135w (85w actual) UFO. It works well in a 2x2 space, supplemented with 4 - 9.5w Cree A19 LED lightbulbs. But, I think Blackstar is overpriced for basically an epi-whatever fixture. I.e., for almost the same price you can get an Area-51 W90 and run it dimmed (I assume they're dimmable). Or, get a generic epi-whatever (Amazon/eBay) for half the price. The problem is that it seems a lot harder today to find those epi-whatever 3w, white backboard lights. Everyone going to "bigger is better" concentrated light (5w diodes, lenses, reflectors, etc.).

I would recommend T5HO before epi-whatever. But, your space doesn't fit T5HO well. The most you could do is a single 2-bulb (2-foot long) fixture. You'd have to add more light.

One of the links I gave above is for replacement T8 tubes. You could run a 36" T8 flourescent fixture with LED replacement tubes. Maybe some LED lightbulbs as sidelight in flower.

I have some fixtures mostly built that Cree A19s would work well in... I might try them...

Tyrone Smith said:

I have some fixtures mostly built that Cree A19s would work well in... I might try them...

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If you're in the experimenting mood, check out the 10w GE BrightStik. I got a 3-pack at Home Depot for $10.50. That's CFL price.

The specs from the packaging don't look good (72-76 L/w). However, the way the diodes are flush mounted and face forward, they avoid the loss of reflecting a Cree 9.5w A19 bulb. And, they're more amenable to removing the diffusor. (The Crees have a protruding tower which begs for accidental contact. The way the BrightStik is flush, it's less risk. But, to be 100% safe with either, it's desirable to power through a GFI outlet. I don't. I think the risk is manageable, especially being recessed in a clamp-on reflector).

I compared one (diffusor removed) to the 9.5w A19 Cree (diffusor installed) and it's 22-25% more light. That's a lot of light for CFL price. The Cree is about 88-90 L/w (with the rubber layer removed from the glass diffusor). That makes the Brightstick close to 110 L/w (for comparison of making both a directional light). That's really a lot of light for CFL prices.

I'd like to grow a plant entirely with these. GE is selling a 100w-equiv, but so far it's only at Sam's Club ($8 per bulb). That would make a good intense top-light. Until then, 18w Cree PAR38 floods work well. But, you have to keep them 8-12" from the canopy. I'm just finishing a PVC "spyder" fixture for mine. I'll tag you when I post about it. The idea is to keep them extended out, 45-degree angle into the top of the canopy. I think that makes the PAR38 flood workable for a space with limited height. You can maintain some of that 10-12" distance from the side.

I really like the bulbs for smaller spaces (or sidelighting taller spaces). After you have the mounting stuff in place, it allows you to use anything you find (anything that might come on the market next year, etc.). You only need 20-30w/sq ft in a smaller area. I think distributing the watts around a plant creates an efficiency, reducing the total watts necessary.

I have an unknown seedling that is starting to pop through so I may play around with that while I try and get some strains I really want.

Thank you for your help

Tyrone Smith said:

I have an unknown seedling that is starting to pop through so I may play around with that while I try and get some strains I really want.

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If you try the 10w GE BrightStik, it's probably better to use a hacksaw to cut the plastic diffuser near the base. Don't cut too deep, just a little all the way around. This teardown shows what it looks like. Because it's all flush, there's not much to hit with the saw. But, I would err on the side of caution. (Cutting 1/4-1/2" up wouldn't interfere much with the light hitting the reflector from the sides either. I have two I want to cut at various heights and see how it affects total reflected light.).

I was grasping the cap and base, and trying to break it in half. I would do that 3-4 times working my way around. It would finally snap open. However, the plate with the LEDs is glued (thermally?) to the base. I found on the last one that the glue can be on the diffusor too. The plate came off with the diffusor cap. It's not a big problem. It slides onto those two prongs. But, I worry I may have reduced the thermal cooling if the clue is also a thermal conductor. (Removing the cap improves cooling. So, I don't know.).

I assume you'll need 3-4 cool to 1 warm (like the Crees). When a seedling, I would start with 1 cool, work up to 2-3 cool before adding a warm. (I started my recent plant with 1:1, and added cool as I went. I felt like it stretched a little too much when I was at 2:1. Next time I'll start all cool.

The Cree bulbs are definitely tried and tested. But, anything will veg. There shouldn't be much risk if you try the GE BrightStik in veg. Based on your experience you could continue with it (1:1 warm:cool) in flower. That would be a valuable demonstration of their ability (or lack thereof). Or, you could use Cree and not risk it.

I think reflectors make a world of difference. Either the clamp-ons I use (integrated into the structure, not clamped onto anything). Or, you could fabricate reflectors from aluminum sheet (like an elizabethan collar used on dogs after surgery. Hose-clamp it to the base socket. The way the BrightStik is so flush, you wouldn't need a tall reflector. 3-4". Some people here use a software app to design optimal reflectors for a light. I bet someone could whip something up. But, I bet it would look something like the molded-in reflector of the Area-51 W-90. A shallow-cup shape?).

If you get into the lightbulb philosophy, you can find other bulbs to try on AliExpress. This company is selling some bulbs. I don't know if they're better. But, it gives you an idea of what you can experiment with. You can find these on AliExpress and other eBay sellers. But, at 25-30w/sq ft with the Crees in a small space (and hopefully the GE BrightStik), I don't think there's a lot of room for improvement.