what is a 400 w ML I hope its not a muk vapor street lamp
Now lets start out with the plants
Unknow , so once they get about 5-8 nodes side shoots , cut off some for clones.
Now mark them and get into cloning , as soon as they have roots put them in to 12 /12 with a bloom fert.

Now with your little plants start out with 600-700 above background ppm if you have 300 ppm tape water make it 900-1000 for 2 more weeks. Then hit them with a total of 1300 over background.
It takes about 3 days for the plants to show what is going on. If they leaf tip burn is none add 150 ppm , till the 1/16-1/8 leaf tip burn. Besure to write that number down.

In 1-1.5 weeks the clones will show sex. Now cull out the males , and reclone. Still keeping the females you had from the start.

Remember to make sure the space is light tight , no light leaks what so ever.
You should be on you way to a good crops
I have used 1300 ppm over background and ph of 5.2-5.8 with a real good incalibrationi meter. NOTE incalibratrion !
Always watch you leafs to tell you what to do
:tomcat: