Plants yellowing

Help i am a new grower and my plants have been in an ebb and grow system. They are under a 1000 watt hps\mh super blue bulb. The lplants are now 4 weeks old and about 5 inches tall with 3-5 sets of leaves. the problem i am having is that my plants are starting to yellow what can i do to fix this. the nutes i am useing are flora nova the grow and flowralicous (sp). If u need more info ljust request the room is at a temp range of 69-82 degrees each day and the humidity ranges from 30-40%. I have a 50 lbs CO2 tank that stays on for 15 min every hour and a half. the room is about 10x11.

How close have you got the lights?

How much nutes you given them? Any chance of pics man?

the lights are about 5 -6 feet above them. I am using 10 ml of the flora nova grow per gallon and 1 ml of the floralicious plus per gallon. My water resivour (sp) has about 25-30 gallons i figure 25 when adding the nutes.