a couple quick suggestions, 1) check the lumen count with a specific instrument you can get at walmart. hold it at the same level as the plants, the top of the plant should get about 800-1000 lumens of light. be sure to check the plants that are farthest from the light since you have only one HPS; 2) maintain a constant air circulation besides just opening the door, a possible O2 surplus could cause darkening of leaves. Ideal color is light forest green, not dark; 3) when watering, instead of guessing, if the top is moist (stick you finger in the soil a little) you can easily determine if the bottom is the same way. lift up the pot a little, and with your finger check the soil at the bottom by just pressing on the exposed soil through which the water exits the pot. If when you touch your finger you can lift water from it, they are moist at the bottom. They are close to being too moist if when you touch the bottom water drips from your finger. Remember the bottom should always be more wet because that is were the water runs (obviously) Try at least the last suggestion as this will ease the question of whether they are thirsty
