4 weeks old plant getting sick

Dear growers,

>I 'm a new member in the forum, mostly because I got a problem with one of my two plants.
>I got them since they were a few centimeters tall and now they are like half a meter. I have them for like 4 weeks and something.

>I 'm having a 400 light working 12 hours a day, I 'm giving them 200-300 ml of water every second day (I mix some green HESI fertilizer inside and also fix the pH to optimum). I also have a fan sending some air on them and a humidifier turned on in the minimum of its power.

>Symptoms: it's been 2 days since one of my plants is not elevating it's leaves anymore, even when the light is on. It still has it's beautiful green color but it seems like it dropped it's metabolic rate down and slowly dying. The lower leaves are completely powerless.
>Also in both plants there are some kinds of small burns in some of the leaves (mostly upper leaves).

>I send the photo links of both plants
>If you have any serious clue about what's going on please let me know.
>If you need more information also let me know.

>Healthy plant: http://imageshack.us/photo/my-images/9/healthyplant2.jpg/
>Sick plant: http://imageshack.us/photo/my-images/259/sickplant.jpg/
>Sick plant closer: http://imageshack.us/photo/my-images/839/sickplant1.jpg/
>Sick plant even closer: http://imageshack.us/photo/my-images/560/sickplant2.jpg/
>Burns: http://imageshack.us/photo/my-images/641/leafburns.jpg/

Thanks in advance,
Petros.

My guess would be overwatering.

Well your soil looks very dry and also looks like underwatering. Might not be though plants in flower tend to have droopy lower leaves they dont get as much light. As for the burns just give them some fresh ph'd water with no nutes. What size pots you using?