Light schedule question

They will definitely benefit from having some down-time... 18/6 is good, I wouldn't go lower than 18. My only other thought here is that this is a pretty dense jungle and it might be good to do a little defoliation - definitely taking some fan leaves that are covering bud sites and also improving the air flow through everything... you don't want to run the risk of bud rot! I'd also try to get the humidity down into the 40s for the same reason... I think everything else looks terrific and you should be happy! Good luck the rest of the way!