Am I doing EI all wrong?

creighton

Guru Class Expert
Jun 18, 2007
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I was under the impression that you were to keep the ppm's of nutrients around these ranges:
N 20-30ppm
P 1-4ppm
K 20-30ppm
Mg 10-15ppm
Ca 10-15ppm
Micro's .5ppm Fe


I add 20ppm K , 20ppm NO3, and 2ppm PO4, .5ppm Fe 3xWeekly. Am I only supposed to add enough of these values to reach a total of these ppm's weekly?

I think I'm doing this right I just wanted to make sure Sorry for the obvious question.

Thanks,
Creighton
 

Tom Barr

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Jan 23, 2005
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Those ranges are fine.
They are non limiting for any light level.
However, if you have less light, say you have 1.5w/gal of T5's, you can easily do with 1/2 that amount.

The goal is to target a level, not keep it precisely at that level the entire time. If it goes a little one way or the other, it should not be a big deal.

If you keep up on water changes and a simple dosing routine that can be consistent with, then this should not pose a problem.

Light drives growth rates which in turn drives uptake of CO2, which in turn drives N uptake and so on down the line.

Regards,
Tom Barr
 

Tom Barr

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Staff member
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Jan 23, 2005
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Well, you have less error when you dose more frequently, and/or do larger % water changes to match the non limiting levels(which the critical value vary based on light intensity).
The thing is, few people account for light, and how the light affects the critical lowest critical limiting value.

The critical value is a point where some limitation becomes detectable for growth rates, it's not evident asap, nor is it a linear response.

Many folks think and assume it is.
Many folks also have no clue how to measure light and have never even done it.

But they want to talk and compare about dosing methods and want explanations about how things can be so different between methods and the responses. They use the fall back " there is a lot we do not yet know about aquatic plants and the complexity of the system".

Screw that, they did not even bother to test the very most basic driver of growth: light.

They rationalize some non answer about how things are so different, yet they did not even consider the basics of plant growth, similarities and how they might be able to answer why there are differences.

Do not fall for that trap.

It answers nothing.
It makes poor assumptions.
It leads to more myth.
Folks wonder why I argue aggressively sometimes, well, that's why.

Regards,
Tom Barr