Well one you mentioned is a great example. In general over a broad range of tanks Pantanal is a nutrient hog. I've had hundreds of conversations with folks regarding Pantanal and 95% of time more dosing improves it. Then you have outliers like Happi and Barr who have grown in it leaner conditions. I've kept the same group of Pantanal in my tank for almost a decade. It's the first to complain if nutrients get too low or CO2 is off. The vast, vast majority of people who grow it well will say the same thing.
And like always these conversations get tricky. You mention Barr's garage tanks and how well they grew Ammania. But I can also send a PM to Tom and get pictures of super healthy Ammania that he has grown in very rich "EI" conditions. If you were to ask Tom or Vin Kutty today how they would start up a new "Dutch" type display tank, it would be with high light, high CO2, and a good amount of nutrients. I know because I have discussed this with them not too long ago.
And in the bigger picture you really need to define what is "lean" and what is "EI" dosing? Very few if any successful people I know dose straight "EI" levels (22:4:22). Xiaozhuang's ATP EI is 14: 4.5 : 15. So less than standard "EI". I dose 12: 4 : 15 just a bit less than that.
Does anyone have a definition for "lean" dosing. Many times I hear people say they dose lean but when I find out their dosing and water change schedule it's not at all what I would think of as lean.
APT Complete is at 6 : 3 : 16. Is that lean? EI? Or something in between.
IMO if you get everything else right you can bet by with a pretty wide range of dosing. More important than the amount is the consistency. Plants take time to adapt to new conditions and in general don't like sudden changes. My guess is that if you set up the same exact tanks and maintain them well the difference between dosing something like APT EI and APT Complete is so small that most would hardly notice.
there is pretty wide range outside EI here are a few I can think off.
1. severely limiting ada style, where one or more nutrient is limiting to induce stress colouration. usually these tanks are N and or P limited. co2 demand is low and in that sense it is more suitable for beginners.
2. less than EI but still pretty rich (i'd consider APT complete to be this. masterline aswell). high K low N decent P. this one will not have any nutrient severely limited, still less demand on co2 and decent growth. may utilise specialised micros and urea (masterline tanks usually use soil, and dennis recommends using osmocote). coupled with rich substrate and decent co2 and light you will grow most plants nicely.
3. minimal dosing. I consider Happis dosing to be like this. decent nutrients in relevant ratios. Nitrogen is high but everything else is much lower than EI. Fe under 0.1-0.2 weekly. N anywhere from 1-3ppm weekly. and K always lower than no3. in this case water changes are minimal, co2 can stay low or high whichever you prefer. you can grow most plants successfully in this approach and tds should stay around 40-60 if you don't have shrimps. if you have shrimps that need gh, tank should stay around 100-120ppm Tds. when done correctly it is very succesful, you may need to use nh4no3, urea, and other chemicals to achieve this results though.
fertilisers such as seachem and tropica use this approach and work very well for most folk.
super healthy Ammania that he has grown in very rich "EI" conditions.
would love to see these photos, I am very curious.
I always thought EI was 30ppm No3, 3ppm Po4, 30ppm K and 0.5ppm Fe?
anyway I think if we can find out what makes the "outlier" tanks work the hobby can advance greatly and it will be repeatable.
just my thoughts.