That's the key is keeping them clean they get build up especially if using tap water I use vinegar and drop of dawn dish liquid works really well happy growing my friend
You can look into ladybugs they work really well but you being that close to harvest. I wouldn't spray them with pesticides myself you can use this why in flower then do bud wash afterwards captain jacks dead bug works
I agree with cannafarmer420 I would stick with 12/12 you can cause them stress and cause them to herm if you're not careful let them ride have you ever heard the old saying you can "love them to death " happy growing my friend