OK, I've slowly backed all the way down to about 44 ml per day, spread over the daylight hours. Things look much better. I did not realize how cloudy the water had gotten, presumably with suspended bacteria.
The RBTA's are largely back to normal, but I did loose one that I'd had for only about a month (not sure if that is related or not, but it could well be). The H. crispa seems back to normal.
The cyano is largely gone.
The green algae on the glass is growing more slowly again.
The soft corals are expanding fully again.
All in all, looking good, and I may add some new livestock (anemones and/or fish) in the next few days.
