the leaves have curled at the sides and some leaves are going yellow some are completly dead . and now the roots on one have grown out the bottom of the pot . there in 12inch pots i have a 600 w hps light 18 hours and water them every 2 days bout 300 mls i just put an extractor fan in the temp is around 25 but before was well over 30 . am i not watering them enough??