Well, EI is for anyone that wants to make use of it, if you have high tap NO3's, no need to add KNO3. You just modify the dosing accordingly to the tap water if it has those nutrients already present.
However,m the underlying principle is still the same, you dose estimations and do water changes to target a range of nutrients to avoid test kits.
EI is not to be taking as set in stone, it's just a routine to avoid test kit issues, which most folks do not bother with as they progress in the hobby anyway.
If you have high NO3's, add K2SO4.
If you have high PO4, no need to add KH2PO4.
High Gh with a good mix of Ca and Mg, do not add GH booster.
And so on.........
This also assumes you calibrate the test kits and can be certain of the test reading.
You have to have good confidence to change routines in your measurements.
If you have higher fish loading, you can likely back off the NO3 as well maybe down to 1/2 for a high fish load at 2 w/gal etc with CO2.
Common sense does apply.
But we all know the issues we hobbyists can easily have that elude all forms of common sense
We all have been there. But being aware of it and making changes that make sense like the above resolve issues easily.
So you just modify EI, but the basic principle is still pretty much for anyone that wants to avoid test kits and does not mind an easy to do water change.
It can and should be tweaked to get the best results(every tank has room for improvement, often for little work/effort).
But pure raw EI should not causes issues for folks either.
Typically CO2 is the issue in most cases.
And if you have higher light(mostly a USA issue), then you can run into CO2 related issues much more frequently.
I have insane amounts of light, but I've had lots of light for decades and am use to it and can reduce and modify it easily these days to reduce growth rates.
I also tend to keep more fish in tanks than most planted hobbyists.
Such tanks get about 1/2 the normal KNO3.
If you are more the daily dosing type, you can do PMDD + PO4 dosing as well and still do the water change at the end of the week.
I suggested this + testing about 12 years ago. Adding EI water change+ dosing principles, you no longer needed to do the testing. Who wants to test water?
Not many.
I've been in the hobby over 30 years and have never met anyone that likes testing water and does it as a hobby for fun.
So you could say that EI is for everyone. Unless you can come up with a method for high growth that is easier and requires no testing.
Non CO2 methods work well ands are for everyone as well. No water changes and no testing.
But slow growth, more patience etc.
Regards,
Tom Barr