Spooky, I just became the owner of a pool and was thinking along the same lines.
Floating measurement device
Solar powered with battery and charging circuit
Arduino
433Mhz Wireless
Initially I think these functions are important:
Ph sensor
Temp sensor
These would be cool:
A way to detect the water level - maybe the anchor being permanently on the bottom could have a REALLY accurate depth sensor or maybe a couple of magnets attached to the side of the pool and the floating lab can work out the level using a magnetic sensor?
Chlorine level - these sensors appear to be expensive, so probably too hard?
A way to detect the force of water coming out of the main pump outlet (to tell you the skimmer is blocked, the sand filter needs a backwash or the pump has issues) - the floating lab could be anchored next to the outlet and there could be a paddle that is moved by the water?
I am keen to get something happening here, thoughts?
Thanks.
Richard