Cory die off

I came home the day after I posted this and 3 were back to normal and 4 bit the dust. The albinos survived the others didn't. No salt but have harder water. That tank is at about 78-80 degrees. no physical symptoms and as far as I can tell they were/are eating fine.
 
are you sure corys dont like higher temps? i keep my tank at 80 with no problems.

+1

my corys are super active and doing great while my tank temp is always 84-86F;)

I have no reasons to why your corys are dying at all, it could be something with your water, some weird problem, r u using ur own RO system or just tap water. U did use conditioner, so unless u r using RO water, and the filters for that haven't been changed, I have no suggestions. Sorry:(
 
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