@corey PM’d me a couple questions that are best answered here. He said:
There’s a lot to unpack here, so please bear with me. You’re best off reading this thread and my build thread for some details. Also, watch all the latest youtube videos from Bruce Bugbee from the last 3-4yrs. I’ve posted most of them in this thread if you want to search for my name and bruce bugbee in this thread. Please make use of the search cuz it really will help you answer all your own questions.
That said, I’m happy to help. Here’s my thoughts:
Q: I read more intense your spectrum is the more resin you will produce. If that’s so do these diy builds put out as much intense light as a 1000k hid?
The amount of resin put out by your plants is mostly due to 1) genetics and 2) environment. Light intensity and spectrum may play a tiny role, but it’s minor compared to the two primary factors. And resin only looks good in pics, it’s not actually important for almost anything related to the effects and/or enjoyment of the weed. The worst looking weed can have the best flavor and effects and potency, since those things are subjective and different for each individual. Looks don’t mean shit to how good it is. The same goes for “lab test” results.
Intensity and spectrum are two different things, but they’re related. The amount of light put out per second (intensity) is measured in something called PAR - photosynthetically active radiation, usually referred to as PPF - photosynthetic photon flux which is the total amount of light the fixture puts out per second. These measurements are used regardless of the type of light. PPFD (add density onto the previous acronym) is the measurement of PPF in a given space - how much light is measured at a given distance from the light fixture, per second.
Here’s an old thread that breaks down all the different types of light measurements. It doesn’t matter if you’re talking about the noonday sun, a candle, a big HPS bulb, or LEDs:
Spectrum is what color of light is produced. It turns out that spectrum is quite a bit less important to your plants than intensity, but it’s somewhat important. The spectrum mostly impacts the shape of your plant and how fast it grows, but only to some degree based on the genetic tendencies of your specific strain/pheno. All blue light generally makes very slow growing, small leaf, compact plants. All red light generally makes very fast growing, large leaf, stretchy viney plants.
In practice, plants prefer green/yellow/red/far red to blue. The more red, the faster plants grow. And the latest cannabis research in university labs shows that you only need about 4-10% of your light output in the blue spectrum to keep plants from getting too stretchy, even if all the other light is red/far red. Far red gives what’s known as the Emerson Effect, which essentially means twice as fast photosynthesis for each far red photon.
So, to the second part of your question, yes, LED lights can easily put out as much total PPF as a 1000w DE HPS. In general, current generation Bridgelux and Samsung and Nichia LEDs are about twice as efficient as HPS. So that means you need only around half the wattage from them to create the same amount of actual light output. That means half the amount of heat, and since it’s being put out across a much bigger surface area, it’s much easier to cool. So you save money on the light output and the cooling needed.
And with all this talk of spectrum and intensity, it’s important to keep in mind that there are many other benefits to LEDs compared to HPS, not just less heat and greater efficiency. Your plants want as many sources of light as possible above your canopy to get the most even PPFD seen by every part of your plants. And, the idea of “penetration” has nothing to do with how intense the light is. Because most colors of light stop with the first leaf they hit, penetration is only a measure of how few shadows there are in your canopy. 1 light makes many shadows. Thousands of lights make very few shadows. Fewer shadows = greater light penetration.
Q: Next question is if I just want to build a light for a 5x5 foot print, just one piece light with the strongest best… how much would I be looking to spend? I need to know that so I can set up a budget plan because I’m on this hid stuff half way through on everything and all I can do is 250 dollars begining of next month.
You’d probably want to build a light very similar to what I built. It’s actually 2 separate fixtures so you have a little adjustability. Check out my build thread, but keep in mind that building it with 1x1x1/8" angle aluminum from Grainger would be cheaper and easier to wire. It cost about $600-700 total and draws up to 720W but you wouldn’t need to run it more than about 600-650w in practice, even in a 5x5. You can veg under it just fine, so don’t be scared by using such low color temp lights. You can grow great weed with anything above 20w/sqft using the current generation of top name LEDs.
Also, you’re much better off buying this stuff at one time, so save your money until you can buy all the parts at once. Parts go in and out of stock and are often discontinued, and LED light builds use very specific parts that you can’t easily swap out.
Hope that helps! 
I think I should start putting these types of responses in their own thread and doing a Wiki so I can link to each post as its own subject from the first post so it’s easier to find (since people don’t use the search feature), then refer people back to it. Do you folks think there’s any benefit to that?
