Tomato nutrient change

Changed the nutrient today. The plants were starting to droop, a sure sign that they need a nutrient change. I'm not sure though if they needed a change. For almost 3 weeks I did not add any water, just to see what the effects are. The nutrient salts concentration may have just become to high for the plants. At any rate, they have a fresh 40 gallons of nutrient. I received a shipment of hardware today, so I plan to transplant the tomatoes into a 4" x 5' PVC fence post ebb and flow of my own design. It's all an experiment, so here goes.