Thanks guys. Thats really confirming what was going round my head. I originally started a thread in plant problems, saying that i thought is was an nutrient def, in particular mg. Several people have suggested canna mg additive. Really appreciate the input, I'm still quite a novice. I've read all the books so I'm an expert on the theoretical but that goes out the window when it comes to the practical as I'm sure you would tell me. Ill keep checking the post and get some mg (epsom salt) additive banged in the tank asap and let you know how it goes. :rastasmoke: