@zboblamont If you are talking about a swimming pool, the chlorine/salt and other chemicals make for a very corrosive environment. so anything mechanical and electrical will not last long!
I want to make something similar (including, salinity, PH value etc) and have found the following from Adafruit: https://www.adafruit.com/product/3827 (not cheap) but if you want to measure the actual level instead of a max or min level as with floats. it might be of interest.
I have not tried it myself,as my pool automation is way down the list of things to do