Veerrrryyy interesting! May I ask about your set up Ralph? No ? A lot of different corals?
Thanks for the interest. Yes, correct, no mechanical or chemical filtration. Just a return pump, heater, lights, thermometer and a gravity-fed ATO. I've run a few different medium sized tanks in the same way for 30+ years...now just keeping it simple and easy with this little mixed reef nano I started back in 2008:
https://www.reef2reef.com/threads/nano-sapiens-12g-ye-olde-mixed-reef.90171/
Ralph.