Replaced MJ-1200 s with Koralia Evo 850 s. After running just for few hours I lost almost all fish, half of my snails.
Here is a little more on what happen.
Either the wider more diapered flow from the Evo injured or stirred up something from sand bed that damaged swim bladders of fish. The lucky fish got trapped under the live rock and died a lot faster than one that where not trapped. Over next 48 hours lost about half of my snails. Only thing to survive where banded snails, one Azure Damselfish, Orchid Dottyback, and all three of my shrimp.
This of course happened on a day where I worked 9 hours in left work dealt with this when I discovered this when I got home, and had to go back to work for another 5 hours after my 3 hour "break" in between.
When I discovered this, only had two damsels left, basslet, dottyback, one surviving Astraea, Turbo, Nassarius, five banded , Fire Shrimp, two Scarlet Skunk Shrimp. I had to remove most of the live rock to get all dead fish. I put the fish and snails into QT, but did not move the shrimp as I figured they would die from the ammonia spike, I also put back the snails. Did 50%+ water change. Put back live rock. One damsel died 3 hrs latter after discovery, leaving one damsel, basslet, and dottyback in QTs. 8hrs after I discovered the basslet died. Turbo and Astraea died 24hrs latter. I left remaining damsel and dottyback in QT until they where swimming and eating normally which took 5 days. So far everything is good with the remaining livestock.
Maybe I should have left them in QT longer, do another 50% water change instead of going back to 10%. What would some of more experienced people have done?