RIP

Sad weekend in the saltwater box.... I feel it is probably my fault but I am not really sure what happened. Friday I changed about a gallon of the water (this is a nano tank - 10 gallons) at the same time I topped off with some freshwater that was a very weak kalkwasser mix. Checked the salinity, tidied up a bit and left the tank a bit stirred up and murky but nothing abnormal.
The next morning my spotted prawn goby was out of his hole dead and the cleaner shrimp was not looking well. (I lost him two days later.)
I don't know what the deal was - The saltwater I used was aged and the right salinity and temp I am suspicious of the kalkwasser mix I mix it very very weak but I am worried that it causes too much of a PH change in a nano tank.
I still feel badly about the whole deal plus my pistol shrimp is now alone.
These guys are not new to the tank, the tank has been up and running for quite a while.
All a big bummer.
I did add an HOB filter with some carbon right after finding the goby but the cleaner shrimp never did recover.
Sometimes this hobby is really irritating!