hps distance with seedlings

wats the best distance from a seedling is a 400w hps light,
at the mo iv got it just over a foot above them and i did a hand temp check and my hand just felt the warmth so im presuming the seedlings will be o.k.

No temp meter or what? I'd imagine it being too hot without serious ventilation/cooling. And get that tin foil out of there.

HPS: 12 - 14 inches, be careful to watch for burns

Soil also drys quickly so watch to make sure plants are receiving enough water.

you can get closer if your light is air-cooled

btw - cutdown - that looks like poorly hung mylar to me but i'm often wrong.