Thank you for the replies!
The shrimp are red rilis.
The tank has been running for just over a year now.
The water temp has been rising, because the house temp is rising. Currently the water is around 80-82. The house AC doesn't kick in until 78 degrees, and we're still in heating weather here! I'm not sure what I can do to lower the water temperature, other than leave the glass lid off the tank.
I will be able to check the kh & gh tomorrow. I don't *think* I have molting issues, because I have seen lots of shed molts around the tank. But at the same time I have lost shrimp for reasons unknown. The last one I saw became lethargic and was dead by the end of the day, without moving from its spot.
Again, thank you all for the help!