White widow 2x 600w grow

Got a 8x6 tent with 2x 600w lights a 10" exhaust fan on a variac a 4" intake fan blowing the cold air onto the bulbs ive got 12 plants in the got more room for a couple more just not got the pots or anything so might add them to the nxt grow there being fed twice in 24hrs for 15 mins im using general hydropinics food the 3 part there just over 2 weeks old from seed theres 2 that are miles behind the rest for some reason hope you all enjoy
Cant get to grips with uploading photos

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I would put them closer together, raise the light a bit and save the electricity cost of running 2 x 600W lights for seedlings instead of 1

Thats a very good suggestion just moved them closer under the 1 light really looking forward to the out come of this 1

Somethings wrong with a few on my babys they have just been turned to 12/12 and some leaves have gone really dry an dying and going brown

I was thinking calcium or magnesium but i put the salts in everytime ive done a water change