how close can i put my 400w hps to my seedlings

[orange wing]

Make it easier for yourself and buy an app named Photon. Once you do that, cut a strip of white paper, wrap it around your phone (they tel u how), and then check the PPFD above seedling

Edit:
Your medium looks a bit rough. I’m certain I can see roots on it too. Cannabis prefers airy medium.

Hi pal i did download app but i never put paper around phone i set it too 280 but i dont think it was right i had to move light up a little and yes thats roots u see im re-using coco im using canazym to break roots down and turn it into food and re-using hydroton

 

[orange wing]

Hi @St. Tom my plants are growing a little slow ive had 30% humidity past week do u think its low humidity. And they was burning because i was spraying sides of pot to higher humidity and back spray was going on them with light on. this is them 2 weeks after other pics leaves are down as light was just coming on they point towards light when on