I'm using a 70w HPS for 4 seedlings and I have 2, 45w soft white and 2, 23w daylight cfls that I would like to add eventually. The way my box is set up the cfls wouldn't be able to be within 2-4 inches of the tops with how the HPS is set up. I was told before that unless cfls are within 2-4 inches that they do no good, and it'll just add extra heat with little light benefits. Is this true? Would it be worth it if they were like 6-8 inches away from the tops?
Light intensity, like all radiation, is inversely proportional to the square of the distance. In other words, having the light 2 inches away vs. 6 inches away, tripling the distance, you cut the light intensity to one-ninth. Just figure out a way to get them closer. If you can't lower the lights, try raising the plants on bricks or pieces of 2x4s or something.
hey thanks, the way I mounted the cfls originally were within 2 inches, but when mounting the hps I didn't think I would need cfls any more so I didn't factor in how they would all be the right distance. Anyways after leaving the cfls in there 5-7 inches away with the hps overnight temp maxed at 88f, and was 75f w/ just the hps so i'm just going to use 70w hps by itself.