HELP!! What Did I Do?!??!

[Beverly]

Had a build up of cyano on the back of my 120g for some time now, so I thought I would scrape it off this morning at about 10:00. Tank got cloudy, but I baste my LR weekly the day before every water change with no ill results from the cloudy water then.

At noon, when I fed the fish, tank was still a bit cloudy, but the fish were all eager to eat.

At 2:30, looked at the tank to find my chevron butterfly dead and removed it immediately Couldn't find the blue sided wrasse and thought it was hiding. Flame back dwarf angel was swimming around the tank, but not with its usual gusto. Green chromis popped its head out of its sleeping place from time to time, seemed to be breathing heavy

Called husband at work and told him the bad news. He came right home and we did a 40% water change, siphoning out the crud from the bottom of the tank. Water was extra dirty compared to a regular water change.

Also took the Hagen 802s out and threw away the foam filter media which was black with crud. Have NEVER seen black crud when doing this task weekly. Broke down and cleaned the 802s as usual. Filled them up with carbon and put them back in the tank. Will remove the carbon tomorrow and replace with new foams.

While doing the water change, found the wrasse dead, removed it immediately Two down, two still alive.

Xenia is doing well as if nothing out of the ordinary is happening, but various mushrooms, button polyps and GSP all closed up.

Just tested ammonia - .5 ppm. Added some Prime to neutralize it.

Will keep an eye on the closed up mushrooms. If they do not improve by tonight or early tomorrow, will discard them.

Sh*t!!!!!!! What the heck happened?!!!??? Everything was fine until I scrubbed off the cyano. Did the cyano build up in the foams cause this catastrophe? Does cyano in the water column become toxic? What is causing the ammonia - the closed up mushrooms?

Feeling pretty bad right now Sure could use some advice, suggestions.

TIA.