The first soil I used had NPK mixture in it, but the one I use now has no added nutrients but I water it with a NPK mixture (when i repotted i mixed the two soils together, the one with no added nut and the one with added nut). I added some bark myself to increase the drainage and in the bottom of the pot i have lava stones used for increased drainage by many growers at the bottom of the pot.
I am using envirolite red 250 w with homemade reflectors, its currently 15 inches away from the plant (had it alot closer before it got burns).
I opened the door of the cabinet and have had it open now for a few hours, humidity went up to 35% and its now 25°celcius from 30°celcius and 18% humidity. I water it daily with nut water and i mist it regularily (once every 3 hours or so when i remember it)
The thing i am most worried about is not the burn spots though but the curling of the leaves and why on earth one of my leaves has started getting yellow spots all over out of nothing, i didnt mist it and i had moved the light before i went to sleep and when i wake up its covered in those dots and many other leaves had some "browinsh" tips on their leaves (think you can see them in one photo if you look closely)
I havent checked the PH of the soil and i dont let the water stand before usage (no need to, icelandic water doesnt have any added chemicals in it)