Update.
So after not running any GFO/GAC for some time, ~2 months, I decided to put it back on line.
A day or two afterwards, I noticed my zoos started staying closed. I watched and waited.
They remained closed and started withering away so I took it back off line. Magically, they reopened. I got a frag of my frogspawn that I had previously fragged for ChrissyPoo(aka o0zarkawater) a few days later. Magically too, the frogspawn seems to be doing well.
So, my conclusion is the combo of GFO/GAC+macro algae, was too much for my LPS and zoos and that is what melted my previously beloved specimens.