Sorry for your lose, I've considered dropping the hobby over incidents like this. I'd just like to throw in source water as the likely culprit. I've seen source water contamination wipe out multi hundred gallon set ups in one go. Rays are susceptible to copper, even a small amount copper sulfate contaminate just once will clear a ray tank real fast. It's the main reason I use reconstituted RO. I don't trust municipal water as I've taken too many losses due to changing safety requirements.