If this was my grow I wouldn't be using LED technology just yet, and typically if using LED on seedlings you'll want to start the lights about 4-5ft above the seedlings to allow them to slowly adjust to the light, if the light has a dimmer switch it might be able to be used in closer proximity, but LED light will scorch seedling within hours of they are too close (running full output), I would start with fluorescent light if I were you, seedlings need some UV light to grow properly from the germination phase, those LED lights haven't quite caught up to basic fluorescent light as far as emitting economical amounts of UV just yet. Fluorescent is still king of UV as far $$$ goes.
While I say this fluorescent lighting is still not ideal on its own, even if mixed spectrum are used they still don't cover the full range of utilisable spectrum that our plants need for growth, this is why I choose to go with a 100% cri incandescent matched up say 1/3 incandescent to 2/3 fluorescent, even 50/50 matched up on the wattage seems to do alright, I've ran a 25w incandescent with just a 19watt 5000k bulb before with no issues, but I would have added more fluoros if I had the room in my cabinet (at the time).
Seedlings don't need high amounts of light, basically 12-15 watts per square foot is enough to keep them thriving as tiny plants, then as the weeks go onwards more wattage is used and increased accordingly, always better to supply ample lighting but most people go overboard initially.
Fluoros are good from about 3ft away, incandescent 25-40 watt can be kept around 2 ft away, but 60 watters do better closer to 3ft distance, you get the picture I'm sure just kind of go slow and adjust the light towards the plant gradually, rather than starting too close it's better to start further than you expect to be ideal, especially with 6500k fluoros and other higher Kelvin range bulb types and so forth.
My exact setup for seedlings is I run a single 24watt 4100k T5 tube setup, with just a tiny 7watt incandescent night light fixture that I rigged up, both about 22" from my plants, however this 4100k bulb is older and isn't putting out the same intensity that a new bulb would do, I'd probably go 2 1/2ft above if it were a new bulb, and then adjust from there, little tips and trick you learn along the way, nobody can really teach you exact, kind of just have to practice on your own to improve on such things, lighting adjustments and so forth, I'm sure a PAR meter would come in handy for this type of thing, I however have never used one and found my way around lighting through trial and error, and while I say this I still make lighting mistakes occasionally, but I'm still somewhat new/intermediate to indoor so I've got excuses, ha ha.
Fluorescent bulbs emit UV on their own, they don't have to be fluorescent reptile bulbs to emit the UV either, all fluorescent light started out as UV light before it strikes the phosphor coating inside the bulb causing a reaction that produces visible light after it leaves the bulb, however not all the UV is kept safely inside the bulb itself even on household fluoros they still release UV but on a much smaller scale, this is exactly what the seedlings need to harden their stems and grow thick leaves, the small amount of constant UV released prepares the seedling for its journey into its life as a plant, withholding UV light from a seedling is detrimental to the survival of that seedling and more than likely will produce an inferior adult plant with slower growth and less overall production, I've seen it occur over and over again.
My advice is to ditch the LED board and allow the seedlings about 1 months growth minimum before slowly adapting them to the LED light source, 1 hour at a time initially , break, then 2 hours, then 2hours twice a day, basically it can take about 1 week or longer to fully adapt to a new light source , so you must do slow at first, that's all I can say for certain. It certainly does take a lot of know how and patience sometimes to make gentle adaptations that lead to beneficial growth and healthier plant growth in the long run, it's all about keeping the growth steady with as few set backs as possible, this is what allows people to achieve heavier yields and faster turnover for their time and effort.
Is that a 3000k LED grow light fixture that you are using now?
