Thanks, will take a look.
It’s a really good question but I can tell you for sure that I am a Goni collector, and when I ran ULN, they were furious they never wanted to open. I thought I was losing all of them. I started dozing, bright, well, neo nitro and within a matter of 24 hours they started to open inside of the week. They were fully expand it again so now I run my tank at 10 PPM and everybody is happy.It is more than 25 years ago and now I work for a company. I don't recall exactly the dosing at that time. I recall that I tried N : P ratios between ca. 12 : 1 and 25 : 1, around the Redfield ratio, and around 15 : 1 caused the least cyanobacteria growth.
If I recall it right my approach was not too different from yours, I wanted to find some nitrate to see it was enough nutrients.
I came to urea because finally it is a kind of non-toxic form of ammonium. And I already knew at that time that urea is involved in many calcification processes.
Before doing the N and P trials I had developed a trace elements formula putting the trace elements into a ratio to calcium and alkalinity supply. From this I knew that urease is a nickel enzyme that is involved in calcification processes by catalyzing the hydrolysis from urea to ammonia and CO2. So why not get both, improved calcification and nitrogen supply, with one compound?
I think especially when dosing amino acids you have to take care of phosphate. Finally amino acids are ammonium + organic carbon dosing at the same time.
The dosing of urea is also not as simple as it may look at first glance. The processing and metabolization of urea by corals and other organisms depends on the trace element nickel which activates the urease, the urea hydrolyzing enzym. Natural levels and even more depleted levels of nickel may activate urease incompletely and insufficiently.