Every year I try growing tomatoes using the Kratky method, and every year toward the end of the growing cycle I fail. The container runs dry, and every year I increase the size of my container. My goal for this year is to have success. I am using a 50-gallon container to grow one beef steak variety of tomatoes. I going with a new rule of thumb. For tomatoes and tomatoes only I am recommending the following: for every foot of plant growth you will need ten gallons of water. For example, if you are growing a larger variety tomato plant (Rutgers, Beefsteak, Cherokee, etc.) and the plant height on the seed pack says five feet, you need a fifty-gallon container.
Many growers on the internet recommend starting the plant in smaller containers and transplanting the plant as it grows bigger in size. I am afraid I have to disagree with this process because you can easily drown your plant. I have used small containers in the past, and when I tried refilling the reservoir of nutrients, my plant usually dies. When refilling the container I am probably not leaving enough room for air, and I always end up drowning the plant. Yes, you can actually drown your plants. That is why I do not recommend refilling or changing your nutrients. Do some research on your own if you have questions about container size or how to change your Kratky system's nutrients.
Thanks for reading!