I have had poor results with FB in comparisons with ADA using EI.
Since EI and good CO2 ruile other potential source as a generalization, the end results are primarily due to the substrate.
That's the key difference when making a substrate comparison.
Alos, there's less transport required when you have nutrients in both locations.
You also have access to NH4 from the soft textured AS.
That is not present in FB or other commonly available products in the USA.
That is likely the increased growth responses we see in some plantas, but it might be texture, but...........if it were texture alone, FB would also give great results, but we just do not see that.
So.......I am left with the presence of NH4 that is added in soil/organic form to the semi soft clay in ADA for the growth enhancement and perhaps some PO4/Fe as well.
I think the AS is very good for folk that neglect their dosing here and there or do not add enough nutrients to begin with.
Many reduce their dosing down to get reds, L aromatica certainly will redden up if you do this, but it looks sort of bad if you do this all the time.
Plants are brittle, sickly, stressed, nothing wrong with that a little bit, but it does not impart a nice example of healthy plant, even if we enjoy the reds.
Some plants such as Mic umbrosum look terrible if you lower the NO3's down.
I have seen this is several folk's tanks, the grass, Rotala green look good, but the Eustrailis, the Mic umbrosum looked terrible in AS and the ADA line of ferts.
I suggested adding soem KNO3, hut they looked at me like I was clueless and that ADA knows all.
Haha, not even. They also had some BGa growing.
Mic umbrosum I know very well to be an excellent indicator for low NO3.
Steve Dixon and myself had noted this about 8-9 years ago when we did some low NO3 test. Many plants reddened up considerable, but this plant also took a beating. Steve had chronic BGA and along the gravel line.
When we bumped the NO3 up, ES lightened up and the Mic started to grow well.
It is a very poor assumption to say all plants will exhibit the precise coloration and growth you want with one given set of nutrient parameters.
Different species of plants have different needs and will respond differently.
Stressed plants typically produce many secondary compounds in response.
My focus has been in higher growth rates, and healthy plants, not stressed out plants.
Stressed out plants will grow redder, slower, something many aquarist admire and personally I think is a bad, it walks a razor's edge of poor health and when adding lots of high light, asking for troubles.
With less light, it is far more mangeable.
But, if you think about it, and having a method that provides the flexibility for both high growth/health, and being able to slow things down and get the reds, slower growth for the photo/open house etc, that is the best of both worlds.
So lower the NO3's down only when you want to max the colors out.
Get the pic, have your friends go OOOooo, Aaahhh and then bump the NO3 back up before you get BGA or stunting.
There's a fine line between slowed growth and stunting and algae.
Many aquarist lack the control and the testing ability/accuracy to maintain that and many of you have way too much light to make that easy.
I've done it with high light, but jeeze...it's not easy testing so much and making sure you are on top of it and keeping such close monitoring.
Some might do it for a few weeks but after awhile, it wears you down and I answered my question anyway about reds/NO3 and mangement.
Less of an issue is non CO2 and low light tanks, then you have less issue, but too many assume high light = more red.........