Mine was saying I needed to get between 2300 - 2800 PPM to be in the green from top to bottom. So far I have only gone as high as 1500 PPM but I did read on another site that tomato's should be between 1400 - 3500 PPM depending on what growth stage your at. If I were to get my reservoir up to those numbers I would have to add 50% more Verti-gro
nutrients than what is suggested on the package.