I am thinking about using dry salts and will ask for advice in a separate thread. But I have a conceptual question about EI targets that is probably irrelevant but it is bugging me I am aware that the targets are simply an empirical estimation. Nevertheless, EI calculators and advice are quite specific about achieving a consistent NPK weekly concentration. If we take as an example the "EI full" targets as defined in the ICF calculator, we find a weekly target of
However, these nutrient concentrations will increase over time until they stabilize according to the actual plant uptake and water changes. If we assume as an example that the weekly NPK uptake by the plants is 60%, and that a 50% weekly water change is performed, then after 4 weeks, the nutrient ppm will converge to these values
This means that after 4 weeks, we have reached an accumulated nutrient ppm that is ~25% higher than the prescribed EI weekly target (see chart below).
With the example above, if we reduce the weekly fertilizer dosage by ~30%, we will converge to the "correct" EI target values after 4-5 weeks. But if we use the prescribed EI weekly dosage, we will be basically wasting 30% of the fertilizers after the initial loading/accumulation period. So, what is the real target we are aiming at? The higher accumulated ppm, or the prescribed EI weekly target?
Am I getting something wrong with this reasoning? Thanks!
- 30 ppm NO3
- 3 ppm PO4
- 30 ppm K
- 10 ppm Mg
However, these nutrient concentrations will increase over time until they stabilize according to the actual plant uptake and water changes. If we assume as an example that the weekly NPK uptake by the plants is 60%, and that a 50% weekly water change is performed, then after 4 weeks, the nutrient ppm will converge to these values
- 37,50 ppm NO3
- 3,75 ppm PO4
- 37,50 ppm K
- 12,50 ppm Mg
This means that after 4 weeks, we have reached an accumulated nutrient ppm that is ~25% higher than the prescribed EI weekly target (see chart below).
With the example above, if we reduce the weekly fertilizer dosage by ~30%, we will converge to the "correct" EI target values after 4-5 weeks. But if we use the prescribed EI weekly dosage, we will be basically wasting 30% of the fertilizers after the initial loading/accumulation period. So, what is the real target we are aiming at? The higher accumulated ppm, or the prescribed EI weekly target?
Am I getting something wrong with this reasoning? Thanks!