You should fill your pots more, after a couple watering and when plants have eaten part of the soil. There wont be much left! and for the mh question they still have the green feeding sacs their a bit young. But plants love mh lamps. so has long as it's not to close it should not be a problem (12"to 16 " is good). basicly you put your hand over the plants if the light is to hot for your hand it's to close to the plants.