I am reading the EI article on this site.
This essentially says that if a plant requires 1ppm per day, then all that is required is that you have at least 1ppm in your tank and the plant won't have any problems. So how does concentration fit into this?
Let's say you have 2 identical tanks, except the concentration of say Nitrate is 2ppm in one tank and 20ppm in the other. Any plant will have 10x less chance of coming across a Nitrate molecule in the 2ppm tank, than it will in the 20ppm tank, simply by virtue of the fact that it has to wait for molecules to drift past.
So surely, having 2ppm Nitrate in a tank with a plant that requires 1ppm will mean it grows slower than if it were in a tank with 20ppm. Taking the example in the quote above, a 1ppm plant in a 1ppm tank will not remove 1ppm from the tank because as the concentration drops off to zero, the plant has to wait increasingly longer for a molecule to arrive.
We can see therefore that if a 20 Gallon tank is lit by 20 watts of light the uptake is slow, let’s say 1 ppm per day as an example. All I need to do is to ensure that the tank always has at least 1 ppm to supply the needs of the plants in the tank. If I added a second 20 watt bulb the uptake demand would increase to perhaps 2 ppm per day. If I continued to only supply 1 ppm per day the assembly line would soon grind to a halt. I need to supply at least 2 ppm per day.
This essentially says that if a plant requires 1ppm per day, then all that is required is that you have at least 1ppm in your tank and the plant won't have any problems. So how does concentration fit into this?
Let's say you have 2 identical tanks, except the concentration of say Nitrate is 2ppm in one tank and 20ppm in the other. Any plant will have 10x less chance of coming across a Nitrate molecule in the 2ppm tank, than it will in the 20ppm tank, simply by virtue of the fact that it has to wait for molecules to drift past.
So surely, having 2ppm Nitrate in a tank with a plant that requires 1ppm will mean it grows slower than if it were in a tank with 20ppm. Taking the example in the quote above, a 1ppm plant in a 1ppm tank will not remove 1ppm from the tank because as the concentration drops off to zero, the plant has to wait increasingly longer for a molecule to arrive.