@Rakie I concur. When I created my low nutrient system, my persistent NO3 and PO4 for my neglected tank was in the range of NO3 80PPM and PO4 4PPM. The problem is once you start the anaerobic bacteria engine. You have to continue feeding the cycle to maintain a healthy reef. The nature of the problem is very similar to nutrients and planted aquarium consider your nitrifying bacteria an engine, you must continually have a reservoir of fuel in the tank to perpetuate the reactor. If you become limited by either NO3 or PO4 the nitrifying bacterial population begins to atrophy. Anecdotally, I have not had trace elements be the limiting factor of the denitrifying process. I literally perpetuate my denitrifying cycle with the product Aquavitro FUEL... Oh the Irony. It is deafening.