lighting distance from plant and more rezin build up

i have a 400 watt light and have plantsgrowing under it but dont know the distance tokeep the light at. and also, i heard if u switch your light back to mh the last two weems of flowering will produce more resin. is this true? thanks.

You should keep your light as close as possible- to tell just put your arm over the canopy if your arm it too warm and close to the light back it up. Switching to mh at the end does help the tric production but IMO just doing a good job growing the plant will beat any gimmic. I'd advise staying with hps, get your temps and light distence perfect then change as little as possible and the plants will reward you.

thanks for the info, will do what u suggested. learn something new every day!

Light height setting varies by watts and ambient temps , air cooled helps maintain a closer stance but you might need it higher if its only one light and you want the maximum footprint .
A good general guideline given is as follows : Low Watt systems 12" max Medium Watt 12"-36 " and large watts at 18"-36" and this is not for air cooled lamps by the way , its an old school rating

Halides make a difference no matter and I highly encourage you to use one and explore . If I could I would grow with nothing but Halides

i appreciate the info, im gonna put it at 12" and see how it grows. thank you.

I think a good rule of thumb is use your hand and start at the light, or however close you can get to it, and back off until you can't feel the heat from the bulb anymore. then back off another 2 inches.

thanks, need all the info i can absorb

400 watt with air cooled has a window of 12-24 inches. That means keep the bud within that range for max budage. I'd take a string with some kind of weight on the end and hang it next to the light at 12 inches. That way a quick eye check every time you lock ends all thoughts of how much they grew. Next Make a ruler or get one at 12 inches and use it to immediate check of the 12-24 range to ensure ur in the window. Little things make this hobby easier and less time in the garden.