well i have a five gallon dwc system. my plant is 5 weeks old and only 5 inch tall... i use the foxfarm line for nutrients. its under a 400 mh. i have a ph tester and tds meter. my ph is at 6.0 humidity is knida low at around 36 %. air temp is steady 72 . and ive only ben up to 500 ppm on tds...