Sf 2000

I transplanted 5 (10-days old from sprouting) seedlings about a week ago and have them under an SF2000. Their canopy height (insomuch as they can even be described as having a canopy at this stage!) is about 6 inches. I also have plants that are about 4 weeks old and have a canopy height of about 18 inches under the same light. This is where the inverse square law comes in pretty handy. Spider Farmer's PPFD map says that at 18 inches at 100%, the center point PPFD value is in the mid 900s. Maybe a little high for 4 week olds, but since the values fall off pretty fast from the center, I haven't worried about it too much. With the light at 18 inches above my veg canopy, it is about 30 inches above my 10 day old seedlings. Spider Farmer says the center point PPFD value for this light at 16 inches is 1168. So, if you double that distance to 32 inches, the inverse square law says the PPFD is going to be 1/4th of what it is at 16 inches - so somewhere around 300 - considering my seedlings are a couple of inches closer to the light than that, they're probably getting something closer to 350 to 400, not too far off the mark for young seedlings and easily dialed in by moving things an inch here or two inches there. Because I have limited space and plants whose date of sprouting differ by as much as 4 weeks, I have to think of ways to work my understanding what generally recommended PPFD values for plants at different stages of development are and how to best achieve all my lighting goals by working distance and/or the dimmer knob. So far everything seems to be thriving, so I'm a happy grower :) With all that said, I'm only on my first grow, so I suspect I'm not telling you anything you don't know - if thats the case, please overlook my droning on and on about this and chalk it up to the enthusiasm of a new grower who is really excited about all there is to learn and know in this new hobby!