it seems to me that my seedlings have stopped growing over the last few days/week. im new to aero so this could be the norm but it seems that im at a standstill. now, my roots are growing nicely. everytime i look i seem to be getting more and more coming in but the plant themselves arent gaining any height or width. room temp is about 68. cloner/rez 68. 50 hum. cfls a few inches above. ppm 400 and ph 5.7. is there any need to be concerned?