400w HPS + Distance

Hi my plants are like 1.5 weeks old. I am using a supernova 400w HPS for veg and flower. how far should my light be from my plants??

About 18 to 20 inches to start. Lower it as they get use to the light to as close as you can get it without them burning. A fan blowing across the light will alow you to get it much closer. But to start let them get use to the light for a few days or so be fore lowering it. Good luck!

KM

ok just so i get it right you are saying 18 to 20inches right? when I look at my measuring stick that comes out to be 3/4 the length of my arm.. now is that right you want my 400w HPS that close? I just want to make sure..

you can put the light as close as you want, the real issue is HEAT. feel w/ your hand to determine if its too hot for your babies, i keep my 1000watt a lil over a foot away - but if you have an air cooled reflector (or one w/ a strip of glass) then you can get them inches away without burning them.

Ok this is what I did I raised them to about 20 inces from the light. See the attached photo...

Now another thing I wanna top my plants. I know it should be done around the third set of leafs. Now does that mean I cut the third or do I cut the fourth?