Solution by Crop

Short answer: yes, but tomatoes are much more demanding than lettuce. They need a stronger solution, a far larger container and regular topping up over several months. Why tomatoes are harder The Kratky method was developed with lettuce, a fast crop that finishes...

Short answer: aim for an EC around 1.2 to 1.8 mS/cm and a pH around 5.5 to 6.5. UF/IFAS suggests about 1.25 mS/cm and pH 5.5 to 6.0 for Kratky growing. What the sources say Oklahoma State University Extension: EC 1.2–1.8 mS/cm, pH 6.0–7.0 for hydroponic lettuce...