As the plant grows the rates of transpiration increases proportionally. but the needs for nutrients does not.. That being said.. At 5-6 weeks I would expect the plants to use 3-4 liters every 2 days. So 10 or so liters a week each plant. In weeks 10-12 that should again be proportionally larger... Goes up to about 20 liters a week in aggressive bloom stages and tapers off again as the harvest time gets closer. No nutrients added mid week at all period..