plz help are my babys dying

alrite smokers.my plants r still growin up and out,butthe bottom leaves r dying.i was told it was either salt build up or nute burn.so 2 days ago i cleaned the all system with fresh water and put fresh nutes in fresh water.i also added some liquid oxygen and superthrive. my ph is now staying at 6 and humidity is 60-75%,temp is 23-27c and ive lowered my cf to 16. what could b wrong with em??? plz help b4 they die

looks like nute burn 4 me m8 flush them again (ammount of water twice bigger as your pot) give them couple of days before u start feeding them again and use less fert than u use to anyway is no point to feed them if they dont need anything and they look healthy and no worries they dont look bad ;]

You can't undo damage already done, the leaves will never go back to lush green ones. Look at the new growth, that will tell you if what you did is working. What kind of water are you using?

thanks....i was using normal tap water at 7.4 ph. but iv jst flushed em again with fresh water at ph of 5.5. iv also dropped down to 6ml per litre nutes instead of 7ml(17 cf instead of 20cf). the new growth at top is fine.nice n green and growing bigger everyday.its jst all the bottom leaves drying out