Yes totally agree with this. You can't get away with just ammonium dosing to replace food. It's just a better way to manage low nitrogen levels in the tank that is already fed well.
----------------
Now....
One of the things that isn't clearly understood is the amount of nitrogen flux through an average aquarium.
I made a thread that got very little traction but it outlines the amount of nitrogen(and phosphate) in a small amount of food.
Hi All, Was just breaking down a specific food I feed to my young fish. They all have tiny mouths currently so PE calanus it is. I was curious how much nitrogen (potential ammonium) and phosphorus (phosphate) was added to my aquarium with each cube. I think the overall numbers will shock you...
www.reef2reef.com
Basically 1 cube of PE calanus adds a little over 1 ppm of nitrogen (potential ammonium) to a 20 gallon aquarium. And that's not much food at all.
Now you might say well it is used by the fish. Well the fact is that heterotrophs are massive nitrogen wasters. Think about an adult fish. If it eats a cube of food then it will release the same amount of nitrogen as ammonium that it took in, as the fish is full size, it's releasing nitrogen at the same rate it incorporates nitrogen. And yes even growing fish will waste most of it.
This massive amounts of nitrogen(phosphate) flux is why I believe fishless coral tanks just end up not working well unless the aquarists understands this and mimics this in some way. (It's way to in depth to go into in this thread but also carbon/vitamin flux needs to be considered as well as mineral bioavailability changes)
So hopefully I haven't come across as saying ammonium is the key to everything. Just a decent tool in the tool chest.