I’m a little late to the party here but I find the idea of Dino “mats” likely being from several different organisms intriguing. I had a crash recently caused by a bad heater thermostat.
The result was four dead fish, a dead anemone and a combination of dinos and cyano. They definitely formed mats together, but I assumed only where I saw red stringy mats mixed with the brown.
At some point I remember reading that dinoflagellates like to form chains, resulting in the dino strings we see. I always figured that the mats were what happened when enough strings came together, catching air bubbles and detritus etc. I’ve got to do a deep dive into this!
Once the crash happened, I got a couple of smaller heaters and cranked the temperature to 84 for 1 week. The dinos died back. Curiously the cyano also died back. I’ve since turned the temperature down to 82. The dinos haven’t come back, and I had a quarter sized patch of cyano come back, which I dealt with promptly. It hasn’t been back since.
I have a good bit of coralline on the back acrylic, and on the sides. There’s also a good bit on the rock too. It’s growing at a good rate. It’s one of many weapons I’ve used to beat the dinos back. Pods and phytoplankton help too.
One last thing. When the crash happened, NO3 was at 30 ppm and PO4 at 0.2. Dinos definitely can and do bloom in high or low nutrient conditions! As I understand it, Cyanobacteria can feed directly from uneaten food, waste, detritus etc. When the sludge goes away, the cyano tends to go with it. I wonder if maybe dinoflagellates can also do this?