You cannot just say, "oh yes give the plants X amount of ppm". Because if you give a small plant 700 ppm, it will DIE very very quickly. (Especially on a .5 conversion scale).
Let me try to explain this by example.
Example 1:
We have a Aeroponics setup with a 20 gallon reservoir with 14 female plants that are currently 4 weeks into the vegetative growth stage. How much nutrients should be in the reservoir? Obviously, you don't want to add too much or they will burn to death, and you don't want to add too little or they will be deficient. So we go ahead and start small, and add 200 ppm. After a day you notice that the ppm meter reads 150 ppm in the reservoir. So you add more nutrients (in the recommended proportial ratios as listed on the bottle) and bring it up to 300 ppm. The next day you notice the ppm meter reads 290 ppm, so you add more nutrients and bring the reservoir up to 350 ppm. A few days pass by and you notice NO change on the ppm meter, but the reservoir water level has gone done considerably (soaked up by the plants). Why did the PPMs stay the same once the reservoir was increased to 350 ppm? Good question.
This means that the plants required a target nutrient concentration of 350 ppm so that the nutrient uptake RATE and water uptake RATE of the plants at this particular stage of growth are perfectly balanced. In other words, the plants would consume just enough nutrients, and just enough water keep the current ratio of nutrients to water in the reservoir at 350ppm. This is how you know you are at the right level of nutrients in your reservoir.
Example 2:
We have a Aeroponics setup with a 20 gallon reservoir with 14 female plants that are currently 6 weeks into the flowering growth stage. What should the nutrients be at? The ppms are currently set at 800 PPMs. A day passes by, and you notice that the PPMs have increased to 950 PPMs. You add some distilled water to the reservoir, and bring the PPMs down to 700 PPMs. Another day passes by, and you notice the PPM meter now reads 750 ppms. So you add more distilled water to bring the total reservoir nutrient concentration to 600 PPMs. A few days pass by and you notice the PPM meter still reads 600 PPMs. What does this mean?
Because the PPM level was constantly increasing when the PPMs were at 800, or 700, this implies that the plants were uptaking more water than nutrients. So more water was added to decrease the concentration of nutrients in the reservoir. Once the concentration (when I say concentration, this means the proportion of water to nutrients in the reservoir) was decreased to a target level of 600 PPM, the rate at which the plants were consuming water and the rate at which the plants were consuming nutrients allowed for the 600 PPM concentration to remain constant. This is the correct reservoir concentration for the plants at this growth stage.
As you can see, using this method is very easy, and it is very easy to apply to any strain, any type of EC meter, or hydro setup. It bases everything on the RATE at which the plants are consuming the nutrients, and water.
Any comments?
