Quote Originally Posted by herbie the love bud
With a 400 watt hps you can set the bulb at 2.5' and leave it there the entire growth. From that distance it will provide the max lumens that a flowering cannabis plant can use.
If your HPS is aircooled then you should get it as close as possible. My 2 400w HPS are within 12 inches from the top of the canopy. The closer the better. But obviously don't burn the plants up. Use common sense.

skeet.
elskeetro Reviewed by elskeetro on . lamp adjustments i have a veg room 4 ft t5..2 cool 2 warm bulbs..u kno..18 hours of light a day..4am to 10pm....all seedlings under a week old on 1/2 strength nutes...condenced powder from gen. hyd. idk some simple stuff..its all on a 2x4 drip irrig. table. i was wondering if i could have a complete layout of e very time you change the distance between the canopy and the bulbs...for a veg room as i have explained and also for a 400w hps 2x4 ebb . flo w/ idk how many plants yet....what distances and at what Rating: 5