Leaves become yellow under hps ?!

[burzuming]

Hey mates I was growing under 150w cfl and soon I switvched to 400 hps but still 18/6. The last two pairs of leaves on my plant are a little yellowish and more thin than the previous. The lamp is 35cm or one foot far from the plants...
Also is there a chance the preflowers to look like male the first few days and than to produce pistils??

[Revanche21]

Hey mates I was growing under 150w cfl and soon I switvched to 400 hps but still 18/6. The last two pairs of leaves on my plant are a little yellowish and more thin than the previous. The lamp is 35cm or one foot far from the plants...
Also is there a chance the preflowers to look like male the first few days and than to produce pistils??

I think they look similar in early stages

yellowish could be a nute problem

[burzuming]

Usually when there are not enough nutrients the lower leaves become yellow. Now only the new ones are(which grew under the hps) Im fed it with nitrogen and iron 5 days ago so that isnt the problem. Havent experienced yellowish leaves under hps?

[hatecable]

If the leaves are turning yellow around the edges and curling then it could be that the hps is a little too close. To get the right distance move the light so that you can hold your hand at the top of the plant for a minute before it gets too hot. Then move it up another 2 inches from that distance and you should be set. Just continue to keep the light that total distance away from the plant as it grows.