i know this is 2.5 years late but.... im using 400w hps as well on 4 GDP clones and im only 5 weeks in flower and got 8-10 inch knots all over and startin to get purp in core and tips of bud (cant see in pics. cell phone camera in HPS spectrum make shitty pics). it may have been the grow tent...
Ive got 4-3' GDP clones 5 weeks in flower in tent with passive intake, good 6" fan and scrubber for exhaust. ona jel in hall way outside room to get escaping smells plus some walmart smelly good things.
whole house reeked.
built home made scrubber from diy odor control forum and connected to...