I remember admiring this thread some years ago.
So sorry for your loss. Awful.
It can happen to all of us.
Not sure about the filtration setup but have you thought of preventing any detritus going into the filters? On a smaller scale I just use plain sponges on the filter intakes which get washed regularly. Filters going anaerobic is what I try to avoid at all cost myself.
The tank is really great and I although you may not feel this way, replacement inhabitants would be really happy to get the chance to be in that tank. I've seen my small fish's reaction when moved from a tiny 20-30G tank to much larger quarters and it's priceless. They start buzzing around like flies on jam. You're going to be able to make other fish's happy as you have done with the others. Accidents happen and we learn from them.
I am so so so so sorry man. I can't imagine losing fish like that after that long. I did have to give up most of my fish that ive been keeping for 4 of my 6 years of fish keeping when I moved to Georgia.