Select a location to grow your tomatoes. Tomatoes grow well hydroponically in green houses, however they can also be grown successfully in grow boxes or in a room where you can control the light, such as a basement or closet room.
Assemble and arrange the equipment that you will need for your hydroponics system. Outdoor systems will need a greenhouse, hydroponic trays and buckets, a fan for circulation, a climate control system to keep the temperature and humidity even and an exhaust system. Indoor hydroponics systems require hydroponic tubs and buckets, grow lights, an exhaust system to vent heat from the room, a fan for circulation, carbon dioxide tanks to supplement the carbon dioxide in the air that plants need to breathe, carbon filters to handle orders, a climate control system and a circuit relay system to prevent power surges.
Score each tomato seed and soak it in water to speed germination.
Wet a paper towel with water and place seeds on the paper towel. Place the towel under a grow light. Keep the paper towel damp until the seeds germinate.
Fill a flood tray with rockwool planting cubes.
Place germinated seedlings in the rockwool planting cubes. Cover with ¼ to 3/8 inch of rockwool. Water thoroughly from above with a watering can filled with water and nutrient solution.
Wait until seedlings outgrow their rockwool planting cubes. Then fill a second flood tray with larger rockwool planting cubes. Dig holes in the center of these cubes large enough to accommodate the smaller cubes.
Remove all but the topmost leaves from the tomato stems. Turn the smaller planting cubes upside down so that the tomato plants are upside down. Pull the tomato plant into a U-shape, being careful not to break the stem, and plant the cube stem side down. New roots will form at each leaf node along the stem.
Repeat this process every time you must replant the tomato plant.
When the tomato reaches a mature size, fill the 3-gallon basket with perlite. Transplant the tomato plant into the bucket. Place the lid onto the bucket so that it supports the tomato plant.
Place the 3-gallon container into the 5-gallon container.
Mix 5 gallons of water with premixed nutrient solution. Pour the liquid solution into the 5 gallon container until the contents are saturated.
Test the pH of the solution daily. By filing a pH tester with liquid solution from the 5 gallon container. Drop a few drops of the pH testing fluid that came with the tester into the water. The testing fluid will change the color of the liquid solution. The shade of the solution's new color will tell you the pH level of the testing solution. If the pH of the solution is too high, you can lower it by adding a diluted amount of sulfuric acid to the solution.
Add more solution as the water level drops in the bucket. Only add enough solution to raise the level of the liquid in the bucket back to it's previous level.
Change the solution for fresh liquid solution every 2 weeks for smaller plants or weekly for larger ones.