Could be residual copper on rockwork and combo of high nitrate(should be between 10 and 40) I had isopods before... did the cleaner shrimp have an orange hue to the underbelly or yellowish legs,you will also take note of a red peble like growth(looks like heart but isn't) inside the shrimp avoid any shrimp with transparent chitin as this is often a sign of an unhealthy invert, on another note did the shrimp hit the air at any time exposing them to direct oxygen is a no no I know it sounds stupid and self explanatory but even I have done this on accident before,it seems to give them accute amonnia burn and then they go into a stasis(comatose like state) stiff and pale blue hue to gills and die soon after....cal looks a little low I like to keep mine between 400 and 450(usually only 20 point shift up or down 420 to 440 how you know the coralite is sucking cal outta water )and mag at 1400 with an sg of 1.025(shifting to 1.024 at the beginning of the the day when cal mag Is chelated and 1.026 at end of day when system is dosed or evoparting off then Rodi is added to maintain 1.025
Personally I'd do a 25 percent then wait a day do a 15 then do a 10 percent to get water stable and add a bacterial buffer to your bottle collection
