Wow

Thanks for all the entertaining and helpful information and the prolification of knowledge (hope my plants grow this well).Starting new into hydroponics, some of your discussions have lead me into new areas of inquisativeness (no I don't use spell check, your mind automatically corrects my mistakes, just like like how we blend primary colors to make others - beside I don't think spell check would find the difference between mental and dental).

I would also like to point out that there is no such thing as a point source it is just a simplification as one dimension becomes great compared to another. (we once thought the atom was the smallest particle but now.....) Now add relfection and refraction with absorption and cancelling....I'll have to dust off my physics book.

So many questions. Where to begin

First my setup will be a 250W 120V Metal Halide, I chose this because I got it cheap($10). I know I will need a new bulb $6.

- My target area is about 4 square feet

- tin foil or mylar to reflect stray rays back and assist in better illumination

I want to know how close I can position the light to the plants? Is there a way to measure to obtain an optimum (temperature, lumens ...?)

On the side:

I'm not sure on the truth of this but as a discussion point. I can see light more in the blue spectrum for growing, more similiar to the summer sun high in the sky, while for flowering leaning more to the red spectrum sun is lower on the horizon. I think nature has had more time to specialize its plants and we need to work with this. Copy it to our best goals.

As a follow up question: Do plants species normal to lower latitudes repond better to blue, versus higher latitude have they adapted differently?

Oh boy, Questions begat questions