When growing in soil, all the microbes and the soil itself assist to make nutrients available to the plant. But when you take out the soil by growing hydroponically, all that unseen hard work by nature is now controlled by the grower. This can prove tricky, but when mastered can be extremely rewarding.

The link below will provide you with information on the importance of plant PH/EC/PPM. (see page 3) 

NFT Hydro – Mixing Hydroponic Nutrient Instructions

Conatct NFT Hydro – lynn@nfthydro.co.za