I keep mine high 36in and what stage are they in? Down load the photon app and calibrate it to Marshydro par map...seedling dli 12 week by week it goes up...12,16,20,30,40,45 and stay at 45 for 7 weeks then lower week by week 40,36, and 32....I calibrate my marshydro fc3000 at 12in with a ppfd...