Thank you for posting the article pictures. Very interesting read. Maybe excess iron can give nuisance algae growth rates a boost.
I used Tech M in a 300 gallon SPS reef and it stayed gone. The tank contents are now in my 465 gallon, and bryopsis is still gone. This was 4+ years ago. Bryopsis can be reintroduced with new corals, etc, as can any nuisance algae. But if it is not in a system to start with, no amount of excess nutrients will bring it back.
If I see it reappear at all in my 93 gallon reef, I will use Tech M just as I did 4 years ago in my 300 gallon reef.
Another point about bryopsis is that it needs very little in the way of nutrients to grow and thrive. IME, having a bryopsis issue is not necessarily an indicator of nutrient issues in the tank, although excess nutrients could certainly cause it to grow faster. My 300 gallon SPS reef was by no means a ULNS system, but was certainly a LNS, as is my 465 gallon tank today.
Algae, including bryopsis and cyanobacteria, absorb nitrogenous waste directly from the water column, so even if you don't have waste in the form of uneaten food, for example, as long as you have fish, corals, and any other critters that continuously produce nitrogenous waste in the form of Urea and release it to the water column, there is food for the algae to consume and grow from, albeit the less nutrients the better.
I have personally never read of anyone that beat Bryopsis with only nutrient control. It seems to be mostly manual removal and chemical control (H202 or Tech M). The occaisional claim that Turbos or some other critters eat it, but nothing I have ever seen personally.
