try feeding them just straight ph 6.4 water for a week until you see lush new growth forming then start on your food program again make suure your ph is 6.4 90% of problems come from ph unless it could be heat stress from your light or not having ample air circulation ? these are all determining factors when you go to diagnose a problem best to keep a calander record what you feed how mush and when what the ph was at is key so you ca go back n then if everything on your food is good then you know its a environmental thing hope this helps