Hmmmm maybe off topic but being a snowmobile/atv enthusiast things run the best right before it blows up
. I think it's the water, does someone live close to you that can pop over with their test kits to confirm?
*edit* Just a quick count you lost 9 fish? or maybe a couple are counted twice. How may fish do you have in a 77G? I realize you have 150G of water with the sump maybe it is a little too close for comfort tempers flare. If you lock 10 poodles in a closet chances of all 10 living pretty slim tempers flare survival of the fittest