Hey again OldSparky,

That was a much better description of the light layout. I now have a much better picture of the light. From a light distribution stand point you need to figure how high above the plants you can run the PP-L lights then do a little ruff math to figure what type of lens angle you need or if you need a lens at all. Your lights have a 8" center to center, so to keep it simple lets say you keep the lights 8" above the plant top. That would mean you need 45 degree minimum and 60 degree would be even better in this case. If the LED has a light spread of 120 degree or more it will loose serious luminous power to the plants.

Your right about the confusing deal between various light sources. It all comes down to total Photosynethetic photons per unit of time, expressed as umols/s (micro moles per second). This is what the scientists use when studying a plant, problem is few mfg's of lights use this. (Theroreme Innovation does) The only person I've seen able to convert the various light sources to this is knna, who was just around before. Not sure the math myself but someone does. Heck, I wouldn't know a micro mole if it bite me in my ankle.

But we can compare most LEDs to each other. Most mfg provide Luminous power in mw (micro watts) so as long as the lens angles are the same you can make a direct comparison. Speaking of that you should check out the 660nm reds from LedEngin, inc and then the prices at Mosuer. You'll find the Osram Dragon plus is a 1w diode and sells for $6.80 or so as a SMD. A 5w Engin is about $12.15 mounted on a MCPCB star. So the Osram may be more efficent watt per watt but is not as efficent $ to $. LedEngin even makes some 15w diodes (tho 660 is no longer available) Weezard used a few of those for a small light setup, their luminous power is measured in WATTS.

As to what ratio is best mixing various light sources, I'll tell you what I told Weezard a long time ago; "As much as I love science and believe in the Law of Physics, when it comes to LEDs there is something of a black art to it." Dat's why we need Weezards, 'ya.

So, there's some more to think abt. I do like your light design, gots lots of potential.:thumbsup:
oldmac Reviewed by oldmac on . Questions for Oldmac - Hi Oldmac ā?? Iā??ve been lurking around here for a while, and decided I needed to join up and see if I can tap into some of your experience. Iā??ve seen that you use a hybrid fluorescent/led fixture and was wondering if there were any pitfalls that you would pass along so that I can jump over them! I have been using a homemade fixture that utilizes (6) 55 watt PL-L lamps, changing out the lamp spectrum based on the plant maturity. The fixture uses reflectors that are 4ā? x 22ā?, and what I Rating: 5