im far from an expert but isnt 20 a bit high?

check this video out

http://www.1-hydroponics.co.uk/video...systems-p1.htm
sc0usa Reviewed by sc0usa on . Why are my leafs curling under? Most of the big fanleafs on my plants,they are starting to curl under.My ph is between 5.8-6.2,and my nutrients are at a CF reading of 20.Im using a flood and drain hydroponic setup,and my plants are 5 weeks old.The thing i want to know is why are they starting to curl under?. :confused: Rating: 5