I have a megaflow 4 sump and the trate readings have always stayed around 80. but they spiked to 180 and fish started dying. The fish that died are emperer angel, peacock flounder, blue hippo tang, blue mandarin, percula clown and algae blennie. the fish that remain are foxface, coral beauty, racoon butterfly, cc starfish and horseshoe crab. The racoon botterfly is starting to lose his scales. I'll take a water sample to lfs today for testing. The fish have been in the tank for at least 6 months, so it has to be something i'm doing wrong. Just can't figure out what. I also took the bio balls out of the sump yesterday, was told that they can hold trates.