PH water to 6.5 DO NOT USED DISTILLED WATER it has no micronutrients in it and the plant needs them. Some yellowing is normal but your yellowing is showing burn from nutes. You are very close to the limit of how much that plant can take. DO NOT GIVE ANY MORE NUTES> You will complete the grow, expect many lower leaves to drop but the buds to stay green and healthy. The plant sends it's reserves to the part that is trying to reproduce and it could care less about the sun leaves any more at this point and it will start dropping them.