The tank was new technically yes but it was seeded with several pieces of established rock.this is what most of us still believe, @MnFish1 has a nice mature tank, I believe last year me and a few fellow reefer including Mnfish1 done a lot of work on nitrifying bacteria. One of the test was to remove a piece of mature live rock and transfer it to a new tank to analyse the ammonia performance of live rock. In that test we adde 2 ppm of ammonia to the live rock and to my surprise it took 4 days I believe for the live rock to transform that ammonia into nitrates. @MNFish could you share the results of the test you done?
His test illustrate that our system can’t deal straight away with increasing ammonia levels. I’m here to show my side of the debate I will expect many to disagree with me although all the evidence is in front of us.
Was not the macro algae tank new wend you had the macro algaes and Cyanobacteria issue? I had a similar event in the past although I was already in the suspicion that my tank wasn’t fully ready to deal with increased ammonia.