All hail the Les Claypool of LED's!! Thank you very much for sharing your knowledge. I read through entire thread over the past couple of days and for every question I had, I pretty much found an answer. If you have a minute, I'd like you to check out some of my questions (written before or while reading) and let me know if my thinking is on track or derailed.
1. What kind of penetration do LED's get?
Fantastic penetration! Just like with HID don't expect a 400w to penetrate further than a 600, and a 600 deeper than 1000w. With a large enough fixture running the correct wattage, 5' tall plants are not an issue.
2. How far away should the fixture be from canopy?
That depends on how much coverage area is needed, how strong the light is and how sensitive the plants are to lighting.
3. Is it generally 1 COB per ft^2?
Yes and No! (Don't you hate that bullshit cockamamie, indecisive reply. LOL) Generally it's 1 COB per ft^2, but this also depends on how much coverage area is needed and how hard you push the lights. Technically 1 COB running at 50% will light a 4'x4' area, but the intensity would be so weak, the plant would get no benefit. If 1 COB provided 1/10th the PAR needed to cover a 4'x4' area, then you need 9 more COB's to properly light the area and that may or may not equal 1 COB per ft^2. That would depend on how big the fixture is.
4. I think I just answered this question, but one of the questions I had was "what dictates how many COB's per ft2? If it was a static 1 COB/ft^2, is that why a 400w, 8 COB CBX3590 in a 4'x4' needed supplementation? I would assume per answer above, yes that's why the 400w needed supplementation, but that same set up running at 500w (just a number I'm throwing out there) as long as that didnt exceed wattage of COB may not have needed supplementation.
5. This isn't really a question, more an observation. Wattage is not where you start with your light, it's where you end up. You don't set out to build a 600w LED to replace a 1000w HID. You set out to build a light with a configuration that's matching or exceeding the output of the 1000w regarding coverage and PAR and it just so happens you built a 600w light. Does that make sense?
These are the questions I couldn't answer:
6. How much did your feed schedule change since the plants received a higher quality of light?
7. On one of the pages you stated 450w of COB driven at 1050 or 1400mA is going to be as good as maybe better than a 600w HPS, 500w COB will spank a 600. Does that also apply to DE HPS fixtures also? Sadly, I've had a
Gavita 6/750 for about a year and pulled my best harvest yet with it, but after reading this thread and a few others, I'm looking to replace it because the heat is a big issue for me.
8. Speaking of
Gavita, can the LEP's be recreated with LED technology? In my ignorance, I'd have to say I dont see the benefit of trying to recreate an LEP if you already have one because the LEP's dont produce a lot of heat nor pull a lot of wattage anyway. My old 300 air cooled LEP aint the problem, its that motherfuckin 6/750 thats a bitch! A beautiful, aggravating bitch that give phenomenal head. LOL
9. Overall, is the 3500K COB driven at 50w the best best for a start to finish grow?
10. Go with CREE CXB3590's if affordable, everything else is second place?
11. Can umols be calculated on paper or do I need a meter?
12. Whats the minimum PPFD needed for our favorite plants?
Thanks again for your time and knowledge. I think thats it for now. Please let me know something I should have asked but didnt. Once I'm closer to actually building a light I might come back for references on where to source parts. How are you liking those quantum boards? See any benefit over a COB?
