Wuts up im new.like my plants?

ok I am wondering why my plants are so short for their age. I have been growing my northern lights plants since oct 4th when i got the seeds in the mail. it is now dec 4th and my plants are only 10 inches tall. They were started in rockwool cubes and ph is 5.8 They have been getting low amounts of ferts but i dont know the ppm yet. They were under a 400 watt mh for the 2 months.they are in 4 inch rockwool cubes and 6 inch baskets with hydroton rocks. I just udgraded to 1000 WATT HPS yesterday, so why are my plants so short? and what can i dop to ensure a good harvest?

I am having roughly the same problem.. 3 weeks of growing and my plants are only like an 1" or 2" tall.. hopefully somone can explain why there is suck slow growth.

pics??? They help a WHOLE LOT!! What nutes? How much is low amounts...how big a system, 5 gal,20gal? How much pumped air per gallon??? Lots of variables, res temp? Relivent temp, humidity? they all play a factor when ya play "God in a Bucket"
Bad ass genetics, or just bad genetics?
Need more info!

jesus youre fast@!