using the BLE temp sensor myBLUE for the pool.
this seems to work:
rpi zero wifi $ 10
sd card $ 5
myBlue temp sensor $20
Put the RPI in line of sight to the pool.
Submerge the my blue sensor 90% into the water. - 1 inch down down does not work. The signal gets absorbed in the water
I still have the old RFXcom pool thermometer and the delta temp is ~ 0.5F
Karl