What is the best distance for seedlings under LED ...

Depending on the light power and heat emission . My setup is a 150w qb board with 2x 50 watt purple light ufo , my temps is around 33°C but can be 35 ( caribbean climate ) and my distance is aprox 60/70 cm from the light for my clones and seedling BUT I did lost 3 of my 10 seedling recently because of the heat that could habe been lower if mu panel has been higher , just for you to have an idea. KingLed website must also tell which is the min / max distance

Hi @farrentino it depends on the power and the heat that your light source emits, the first 2 weeks they don't need a lot of light intensity, the top of the pots should be 25c of temperature. good luck mate 👍

Yo, i can see you have strong Led light KingLed 1000W so i don't recommend you to go lower then 80 cm from the plants. i usually hold my Leds around 100-120 cm from the seedlings. But i'm not a specialist from light check other opinion too. good luck ✊✊😀

Go to the manufacturer for that