..hi im a little confused about ppm too ..mine are two weeks bubba and same as pic leaf for leaf.. but my ph is 6 and cheked my ro water and rez ..and they are both same ph and ppm.. 1600ppm wtf??I need some help. I do give them nutesThanks for your response guys. My plants are about the same size as on the picture. How much ppm should I give them? They are in rockwool cubes in nft system. Some roots are showing in the bottom of the cubes. I will use RO water.