400w HPS distance until bleaching effect?

what is the closest u can have an HPS to the canopy if heat isn't and issue?

By saying heat is not an issue, I assume you have adequate exhaust and ventilation systems in place.
Generally 12 - 15 inches above the canopy is sufficient.

A good way to make sure the temps are ok is to use your hand.

Place it under the lamp, and see how close you can get to the light without feeling the burn on your hand.
The canopy should be no closer than this.

If it can burn you, your plants are no safer!

right i gotcha the little hand trick is awesome and the hps is air cooled so the hand can get pretty close for a good amount of time and feel no heat.

just wanna know how many foot candles it puts out vs distance vs what the plants can take

i heard 400 watt lights lose lumensat like 24 inches... i could be wrong but its a chart that shows lumens,watts,distance

heres a graph i found on another post

6" from a 400 watter I got bleaching.

1' seems the magic number REP!!!